Yes, they're out already.
The 20-man raid zone is the southern part of Silithus, beyond the Scarab Wall.
The 40-man raid zone is slated to be a little bit more difficult then BWL and is the temple inside the 20-man raid zone.
Guessing it's the usual "get attuned to" setup that everyone needs to go through.
From what I've read it states that every single player on the server needs to pitch in, in order to open up the Scarab Wall so that the entire server can finally enjoy the two new raid zones.
It's a process that can take at least one week in which everyone's working on the effort 24/7.
Uberguilds have to do their own "uber thang" and deliver whatever is most obscure while the little peons just pitch in with ordinary and trivial turn-in quests or something.
Ahn'Qiraj is slated to be patched in with the next content patch - version 1.9.
