Personally, I'm pretty convinced that the forthcoming expansion is going to be called Wrath of the Lich King, mostly because the title was listed by the USK, the German equivalent of the ESRB (see update 2 here). Now we have what purports to be a leaked FAQ for the expansion, allegedly briefly visible on wow-europe.com last night. I don't know whether this is real or not, but it's certainly interesting. Here's my favorite part (my emphasis):
 
 
The death knight is the first hero class in World of Warcraft; once certain criteria are met, players will unlock the ability to create a new death knight character, which will begin play at a high experience level.
 
That answers the question about people having to grind the new class up through the levels. I only wish it was available for all classes. According to this FAQ, the DK will be available to both Alliance and Horde, and will "combine damage-dealing and tanking" as far as party role goes. A few other points of special interest (summarized):
 
Level cap raised to 80
New profession: "Inscription allows the player to permanently enhance their spells and abilities and to create mysterious items of power to use, trade, and sell."
New and existing characters will be able to customize dances (??) and hairstyle
Northrend will be about as big as Outland and will take about as long to complete.
Players will fight Arthas himself
The full FAQ is after the cut, or you can read it at the source here (scroll down for English). Please do remember to take this with a grain of salt.
 
FAQ for World of Warcraft: Wrath of the Lich King
 
What are the features of the new expansion?
 
Wrath of the Lich King builds on the rich foundation established in World of Warcraft and The Burning Crusade, providing a wealth of new content for players to explore. The harsh, forbidding continent of Northrend, home of the Lich King and his undead minions, will be uncovered on the world map, and to contend with the new challenges found there, players will be able to advance to level 80, acquiring potent new abilities and talents along the way.
 
In addition, Wrath of the Lich King will introduce the death knight hero class to World of Warcraft. Once certain criteria are met, players will be able to create a new death knight character, which will start at a high level. Furthermore, player-vs.-player battles will reach a new level of intensity with the addition of siege weapons and destructible buildings, not to mention a new battleground. There will also be an abundance of new quests, dungeons, monsters, items, and recipes -- as well as a new profession, inscription -- for players to try out. The expansion will include some additional character-customization options for players as well. We'll be going into more detail on all of these features in the months ahead.
 
How will the death knight class fit into the game?
 
The death knight combines martial prowess with dark, necromantic energies. Players might be familiar with the death knight from previously released Warcraft games -- most recently, in the campaigns for Warcraft III: Reign of Chaos and the Frozen Throne expansion, the former paladin Arthas became a death knight and wreaked havoc across Azeroth and Northrend before fusing with the spirit of Ner'zhul to become the Lich King. The death knight is the first hero class in World of Warcraft; once certain criteria are met, players will unlock the ability to create a new death knight character, which will begin play at a high experience level. We're currently exploring various options for how the death knight will play and the types of abilities at its disposal, and we'll be revealing more information about this new class as we get further along in development.
 
Will the death knight have any abilities from previously released Warcraft games?
 
The way we portrayed death knights in past Warcraft games is certainly a source of inspiration, but we are still determining how best to capture that feel within the mechanics of World of Warcraft, and haven't made any final determinations on specific abilities.
 
What role will the death knight play in groups and raids?
 
In general terms, the death knight can be considered a type of class that combines damage dealing and tanking, but naturally it will have an array of unique abilities as well.
 
What races will be allowed to play death knights?
 
We haven't yet made a final determination about which races can be death knights. However, the class will be available to both the Alliance and the Horde.
 
Will there be additional hero classes in the future?
 
Yes, we do intend to add more hero classes in the future, but right now our focus is on the current expansion.
 
What is the story background of the expansion?
 
Players last visited Northrend in the Warcraft III expansion, when Arthas Menethil fused with the spirit of Ner'zhul to become the Lich King, one of the most powerful entities in the Warcraft universe. He now broods atop the Frozen Throne, deep in Icecrown Citadel, clutching the rune blade Frostmourne and marshaling the undead armies of the Scourge. In Wrath of the Lich King, the greatest champions of the Alliance and the Horde will do battle with the Scourge amid Northrend's howling winds and fields of jagged ice, and ultimately face the Lich King himself.
 
Will players actually get to encounter Arthas himself?
 
Players will be skirmishing with the minions of Arthas from the moment they set foot on Northrend. He will be a constant presence as players progress through the expansion content -- which will culminate in a showdown with the dread Lich King himself.
 
Can you discuss some of the new talents and abilities that will be available from level 70 to level 80?
 
As with character advancement up to level 70, players will gain access to an array of potent and exciting new abilities and talents as they make their way from level 70 to level 80. However, it's still too early to get into specifics on these.
 
How long will it take to advance from level 70 to level 80?
 
We were pleased with the pacing from level 60 to level 70 in The Burning Crusade, and we intend to take a similar approach to pacing character advancement in Wrath of the Lich King. However, the specific amount of time that it will take players to reach level 80 will vary widely based on play style.
 
What can you reveal about Northrend?
 
The first area of Northrend we're showcasing is the Howling Fjord, a region of grasslands overlooking massive cliffs at the southeastern edge of the continent. This, along with the Borean Tundra, is the front line of the war against Arthas, and players will come face to face with his minions as soon as they set foot on Northrend. Eventually, as players progress further, they will explore the Grizzly Hills, Dragonblight, and more. We'll be showing off some of these new areas in the months ahead.
 
What's the level requirement to enter Northrend?
 
Players of any level who have purchased the expansion can visit Northrend. However, all of the content is designed for players level 68 and up.
 
How many new dungeons will be in the expansion?
 
The first dungeon players will enter is Utgarde Keep, which is intended for five players around level 70. Utgarde is inhabited by the Vrykul, a Viking-like race bent on proving their strength to the Lich King, who will raise the most worthy of their warriors to serve him beyond the grave. We intend to provide a variety of dungeons comparable to that in The Burning Crusade and will be revealing more details about some of these in the months ahead.
 
Do you plan to continue with the 25-player model for raids?
 
Yes, we've been pleased with the tactics, intensity, and variety of the 25-player raid model, and plan to continue with it.
 
In what ways will players be able to further customize their characters in the expansion?
 
In addition to the numerous new character-customization options that will be available with all of the new weapons and armor added by the expansion, we'll be offering some fun ways to alter both existing and new characters with regard to dances and hairstyles, but we're not ready to go into more detail just yet.
 
What can you reveal about the new profession coming with the expansion?
 
Inscription allows the player to permanently enhance their spells and abilities and to create mysterious items of power to use, trade, and sell.
 
What can players expect with regard to player-vs.-player combat in the expansion?
 
Players will be able to take control of siege weapons and use them to destroy opposing buildings, adding a new layer of complexity to PvP battles. Naturally, we'll be providing some fun places to put these new tools to good use, and we'll be revealing more information about them in the months ahead, in addition to the new battleground content being added.
 
Can you give a sneak peek at the new recipes and items in the expansion?
 
There will be hundreds of new recipes and thousands of new items available, but we're not ready to discuss specific examples just yet.
 
How many zones will be in the expansion?
 
Northrend will be roughly equivalent to Outland in terms of size and scope.
 
Will there be any new cinematic scenes?
 
Yes, our cinematics department is hard at work preparing a new intro movie for the expansion.
 
Release/Availability
 
Do you need to own the expansion to play with friends who have it?
 
There will be many aspects of the expansion that will be available to all players. However, in order to experience certain content, such as Northrend, or be able to play as a death knight, players must purchase the expansion.
 
Will there be an open beta test of the expansion?
 
We have not yet determined whether the expansion will require an open beta test. If we do decide to conduct a beta test, details will be posted on the official World of Warcraft website once we've gotten further along in the development process.
 
When will the expansion be released? How much will it cost?
 
We have not yet announced a release date for the expansion set. However, we expect to announce further details, including the release date and price, on our community website in the months ahead. Please stay tuned to worldofwarcraft.com for more information.
 
Will there be a collector's edition?
 
We have not yet made any determination about whether there will be a collector's edition of Wrath of the Lich King. We'll be announcing details such as this closer to release.
 
Will a Mac version be available simultaneously with the PC version?
 
Yes. As with all of our games, Wrath of the Lich King will be compatible with and optimized for both the Windows and Macintosh platforms.
 
What are the system requirements?
 
We'll continue to ensure that the game is playable on a wide range of hardware. However, we have not made a final determination on the system requirements as yet.
 
Will the expansion be released globally at the same time?
 
We recognize that players throughout the world will be eager to experience all of the new content being added with Wrath of the Lich King, and we will make every effort to release the expansion simultaneously worldwide. However, there's always the possibility that unforeseen circumstances could delay the launch in any given region. We'll share the launch timing with players in each region as soon as the plans have been finalized.
 
What is the ESRB rating for the expansion?
 
The expansion has not yet been rated by the ESRB. However, we anticipate that it will receive the same rating that the original World of Warcraft received -- "Teen."