For Druids, the Lifebloom healing coefficient has been reduced. It'll be interesting to see how much. Rolling Lifeblooms have been the healing method of choice for most discerning trees, but if the nerf is severe enough, perhaps we'll see some return to Regrowth and Healing Touch. In other changes, Feral Druids are heading further and further to side of agility, with Nurturing Instinct now increasing your healing spells by up to 100% of your agility, and increasing your healing received by 20% of your attack power while in Cat Form. This seems like it may make Cat Druids at least a bit less squishy in PvP, if they're paired with a healer or can find a spare second to duck out of the fray and heal themselves.
Lots of additional changes after the break!
For mages, Blink, Slow, and Spellsteal are now lower in mana cost.
Chastise, the spell that replaced Fear Ward for Dwarves and Draenei, has been changed. Now instead of a 2 second disorient, it will provide a 2 second root. In some ways, it is a bit of a nerf since now those affected can still keep attacking, but it will also allow the priest to keep attacking and shouldn't, in theory, break immediately on a DoT tick or stray AE damage like Chastise did.
Tremor Totem will pulse every 3 seconds now, down from 4, for Shamans. We'll see how much difference a second makes, but it should at least give a slightly lower chance that a feared ally will run out of range of the totem before it pulses. However, Elemental Shamans will have a harder time chaining Nature's Swiftness and Elemental Mastery for massive damage, as the two now share a 10 second cooldown.
The Rogue Improved Backstab talent is now renamed Puncturing Wounds, and will increase critical strike chance with Mutilate by 15% at the highest rank as well as increasing Backstab critical strike chance by 30%.
In non-class news, you'll now not have to deal with a cooldown in transmuting Arcanite.
The changes haven't actually made it to the Test Server themselves at last check, but since the patch notes are updated, we can probably expect them to go in soon. We'll be interested to see what the classes themselves think of these, and we'll be on the lookout for more progressive changes as testing continues. Stay tuned!
Update: One more change (it's been rumored in the past but is now official!) is that Paladin Turn Undead will be renamed Turn Evil and work against Demons. Felhounds may not make quite the meal of Holy Paladins that they did before.