One of the things that was only briefly mentioned at the recent WWI was the new physics engine. Just my guess here, but I reckon that WoW and Diablo III will be sharing a common physics engine; in Diablo III "environments will be interactive and destructible"; Lake Wintergrasp will have "destructible elements such as bridges and keeps". So it's worth keeping an eye on Diablo III and WotLK features to see what might get shared across.
One of the things that players loved about Age of Conan was the knockback. For those who haven't played, this allowed you to throw mobs in front of you back a few feet with a temporary stun - way cool fun even if it had its problems with positioning in a game which had collision detection. Now what do I see here? Death Knights have a Death Grip ability "drawing the target toward the Death Knight".
You heard it here first... Blizzard will reverse that mechanic in a future patch to bring knockback to WoW. Funcom must be so pissed!
And in the new Dalaran arena "a blast of water will push people out of the pipe"? That's not as new as the DK ability I admit. Anybody who's been to Magister's Terrace has had their toon pushed around or floated in anti-gravity... heck, even Baron Geddon was pushing us around (up) back in the day.
What is new, though, is the ability for players to start doing these things to the mobs instead of the other way around.
- Healer's Haven - Holy Priest Talent - The priest explodes with divine light throwing back any attackers and temporarily stunning them.
- Breathing Space - Prot Warrior Ability - The warrior spins in a crushing arc slamming attackers to the ground.
- Force of Nature - Shaman Totem - Lasts 30 seconds. The totem pulses every 5 seconds pushing back nearby attackers.
- Fatal Attraction - Prot Paladin Talent - The paladin's charisma shines forth, dragging nearby enemies toward them in a daze which slows their attack speed.