Let's see what's goin' on here...
1. Zul'Gurub and Zul'Aman are being updated WITH WHAT APPEAR TO BE NEW BOSSES, IT'S NOT JUST A RECYCLE. IT'S LIKE DEADMINES AND SFK.
2. Caster Legendary damn-near confirmed for Caverns of Time.
3. Hydras tamable by Hunters.
4. Lots of new pets, some new and returning mounts, and new pet-collecting achievements.
5. Tying into the pet thing, looks like the Winterspring Frostsaber mount will be renovated to act like the current Venomhide Ravasaur daily quests. This most likely means it will take at least 20 days to get the mount but will require much less work on your part, as opposed to what used to be an indefinitely long grind but became a 5 day grind and is now a 2 day grind. Glad I have mine already.
6. Various class changes, as expected.
I just have one gripe: How long before I can solo ZA and ZG for the mounts again? I have luck issues, even more prominent with the cataclysm rare drops.