We are trying to make haste a slightly more attractive stat for classes that utilize a lot of damage or healing over time spells, specifically Shadow priests, warlocks (though especially Affliction) and Resto druids. We realize other classes use hots and dots too, but I think we can all agree that it's a bigger problem for the ones I mentioned.
 
I'm going to share with you an idea that the class and item designers came up with for 3.3. This is a work in progress so it's possible we'll end up going a different way after we see how it plays. However I also wanted to explain our logic here in case it wasn't obvious.
 
We have new tech that will allow specific hots and dots to tick faster -- the time between ticks would decrease. This means more damage or healing per time but also having to refresh those spells more often. Since there is a trade-off, we're not sure the change is a no-brainer, especially in the healing case.
 
Because of this, we are planning on introducing the concept through glyphs. Glyphs represent a great test bed for new ideas because they are easier to change (and easier on the players when we do change them) compared to core spell functions or even talents. If we like the way it feels and players like the way it feels and the glyphs prove popular or fun, then this may be the kind of thing that shifts from glyphs over time -- not unlike the way some favorite set bonuses eventually become talents.
 
For 3.3 we are talking about introducing three new glyphs for Shadow Word: Pain, Corruption and Rejuvenation that would allow these spells to tick faster with the more haste you have. There are glyphs of Corruption and Rejuv already, and we're not sure how we're going to resolve those yet. For Shadow Word: Pain, we are likely to rename the current glyph to Glyph of Mind Flay, remove the old Glyph of Mind Flay, and increase Mind Flay by 10 yards in the base spell.
 
Again, these are not promises (nor ponies). For a variety of reasons, you may see these changes on the PTR or you may not. If you do see any or all of the three glyphs implemented however, we wanted you to have some idea of what we were trying to do. Feedback is certainly appreciated, especially if you get to try them out.

Scourge Strike: Redesigned. The base ability now deals 50% weapon damage plus an additional amount as physical damage. However, for each disease the death knight has on the target, the target will take additional shadow damage equal to 25% of the physical damage done.

   * Conflagrate: Redesigned. This talent now consumes an Immolate or Shadowflame effect on the enemy target to instantly deal damage equal to 9 seconds of Immolate or 8 seconds of Shadowflame, and causes additional damage over 3 seconds equal to 3 seconds of Immolate or 2 seconds of Shadowflame.

Tier 10 Set Bonuses
 Death Knight
Item - Death Knight T10 Tank 2P Bonus - Increases the damage done by your Death and Decay ability by 20%.
Item - Death Knight T10 Tank 4P Bonus - When you activate Blood Tap, you gain 12% damage reduction from all attacks for 10 sec.
Item - Death Knight T10 Melee 2P Bonus - Your Obliterate, Scourge Strike, and Death Strike abilities deal 10% increased damage.
Item - Death Knight T10 Melee 4P Bonus - Whenever all your runes are on cooldown, you gain 3% increased damage done with weapons, spells, and abilities for the next 15 sec.

Druid
Item - Druid T10 Restoration 2P Bonus - The healing granted by your Wild Growth spell reduces 0% less over time.
Item - Druid T10 Restoration 4P Bonus (Rejuvenation) - Each time your Rejuvenation spell heals a target, it has a 2% chance to jump to a new target at full duration.
Item - Druid T10 Balance 2P Bonus - When you gain Clearcasting from your Omen of Clarity talent, you deal 10% additional Nature and Arcane damage for 6 sec.
Item - Druid T10 Balance 4P Bonus - Reduces the cooldown on your Eclipse talent by 6000.
Item - Druid T10 Feral 2P Bonus - Your Swipe (Bear) and Lacerate abilities deal 20% additional damage and the cost of your Rip ability is reduced by 10 energy.
Item - Druid T10 Feral 4P Bonus - Your Enrage ability no longer decreases your armor and instead decreases all damage taken by 12%, and the periodic damage done by your Rake ability can now be a critical strike.

Hunter
Item - Hunter T10 2P Bonus - Your Auto Shots have a 5% chance to cause you and your pet to deal 15% additional damage for until cancelled.
Item - Hunter T10 4P Bonus - Your Shot abilities deal 4% increased damage to targets afflicted with Viper Sting, Serpent Sting, or Wyvern Sting.

Mage
Item - Mage T10 2P Bonus - Your Mirror Image ability also causes you to deal 15% additional damage for 10 sec.
Item - Mage T10 4P Bonus - Your Hot Streak, Missile Barrage, and Brain Freeze talents also grant you 12% haste for 3 sec when the effect of the talent is consumed.

Paladin
Item - Paladin T10 Holy 2P Bonus - The cooldown on your Divine Favor talent is reduced by 60 sec.
Item - Paladin T10 Holy 4P Bonus - Your Holy Shock spell causes the next Holy Light you cast within 10 sec to have 0.3 sec reduced cast time.
Item - Paladin T10 Protection 2P Bonus - Your Hammer of the Righteous ability deals 20% increased damage.
Item - Paladin T10 Protection 4P Bonus - When you activate Divine Plea, you gain 12% dodge for 10 sec.
Item - Paladin T10 Retribution 2P Bonus - Your Seals and Judgements deal 10% additional damage.
Item - Paladin T10 Retribution 4P Bonus - Your melee attacks have a 4% chance to reset the cooldown on your Divine Storm ability.

Priest
Item - Priest T10 Healer 2P Bonus - After your Pain Suppression and Guardian Spirit talents expire on your target, they grant your target 10% increased healing received for 10 sec.
Item - Priest T10 Healer 4P Bonus - Your Flash Heal spell has a 15% chance to reset the cooldown on your Circle of Healing and Penance Spells.
Item - Priest T10 Shadow 2P Bonus - The critical strike chance of your Shadow Word: Pain, Devouring Plague, and Vampiric Touch spells is increased by 5%.
Item - Priest T10 Shadow 4P Bonus - Reduces the channel duration and period of your Mind Flay spell by 51%.

Rogue
Item - Rogue T10 2P Bonus - Gives your melee finishing moves a 13% chance to add 3 combo points to your target.
Item - Rogue T10 4P Bonus - Your Tricks of the Trade ability now grants you 15 energy instead of costing energy.

Shaman
Item - Shaman T10 Restoration 2P Bonus - Your Riptide spell grants 20% spell haste for your next spellcast.
Item - Shaman T10 Restoration 4P Bonus - Your Chain Heal critical strikes cause the target to heal for 25% of the healed amount over until cancelled.
Item - Shaman T10 Elemental 2P Bonus - Your Lightning Bolt spell reduces the remaining cooldown on your Elemental Mastery talent by 1 sec.
Item - Shaman T10 Elemental 4P Bonus - The cooldown on your Lava Burst ability is reduced by 15 sec.
Item - Shaman T10 Enhancement 2P Bonus - When you activate your Shamanistic Rage ability you also deal 12% additional damage for 15 sec.
Item - Shaman T10 Enhancement 4P Bonus - Each time the beneficial effect of your Maelstrom Weapon talent reaches 5 charges, you have a 15% chance to gain 20% attack power for 10 sec.

Warlock
Item - Warlock T10 2P Bonus - The critical strike chance of your Shadowbolt, Incinerate, and Corruption spells is increased by 5%.
Item - Warlock T10 4P Bonus - Each time your Immolate and Unstable Affliction spells deal periodic damage, you have a 15% chance to gain 12% spell haste for 10 sec.

Warrior
Item - Warrior T10 Protection 2P Bonus - Your Shield Slam and Shockwave abilities deal 20% increased damage.
Item - Warrior T10 Protection 4P Bonus - Your Bloodrage ability no longer costs health to use, and now causes you to absorb damage equal to 20% of your maximum health. Lasts until cancelled.
Item - Warrior T10 Melee 2P Bonus - When your Rend and Deep Wounds abilities deal damage you have a 2% chance to gain 20% attack power for until cancelled.
Item - Warrior T10 Melee 4P Bonus - You have a 20% chance for your Blood Surge and Sudden Death talents to grant 2 charges of their effect instead of 1 and for the duration of the effect to be increased by 100%.

Item - Warrior T10 Protection 2P Bonus - Your Shield Slam and Shockwave abilities deal 20% increased damage.

Item - Warrior T10 Protection 4P Bonus - Your Bloodrage ability no longer costs health to use, and now causes you to absorb damage equal to 20% of your maximum health. Lasts until cancelled.