Some of the changes from 2.1 are going in early. Specifically, Tigole announced that they are hotfixing some raid things:
Because 2.1.0 is not yet on the PTR's (we're hoping by tomorrow or early next week), we're going to hotfix the base creature respawn in Serpentshrine and TK Raid to be 2 hours. We're also going to fix the bug that's causing the creatures to respawn after the boss for the corresponding section has been killed.
These aren't all of the changes that we have for 2.1.0, just two of the ones that we will be able to hotfix. There are more changes coming in 2.1.0 that include creature tuning, better loot etc...
Lots of the creatures have fewer hitpoints
Lots of the creatures are no longer immune to CC (The female naga in SSC can be poly'd, Skeletal Ushers in KZ can be shackled)
Lots of bug fixes
The most interesting bit in this post, though, to my eye, is "Because 2.1.0 is not yet on the PTR's (we're hoping by tomorrow or early next week)." See? PTR next week! What'd I tell ya. Of course, now that he's said this, if we don't get a PTR by Wednesday the forums are going to explode in a fit of angst, which is why Blizz never gives ETAs. I hope they can meet their target on this one, since 2.1 looks like it will be a fun patch for most parts of the game. Once the patch hits PTRs it'll be at least a week or two before it goes live.
Pictured above, by the way, is Al'ar the Phoenix God, a boss in the Eye (the 25-man "TK Raid" referred to by Tigole) who is suspected to drop a 310% speed flying mount called "Peep the Phoenix Mount."