Aus dem NY Times Interview mit Tigole:
Q. What can you tell me about Naxxramas?
A. Naxxramas is going to be the most difficult thing in the game until the expansion pack comes out. It will be the pinnacle, and it's absolutely massive. You'll see this big necropolis floating above Eastern Plaguelands. It's a 40-man raid zone, and it's bigger than the Undercity [one of the main cities in the game]. Things could change, but we're up to something like 18 bosses in there, and they are really cool, too. But it's going to be hard. Really hard. We're hoping to release it in the spring.
Q. Will we need to open Naxxramas with a big farming event like Ahn'Qiraj?
A. No. Naxxramas will just be open. But we do want to do a world event, which we want to call the Scourge Invasion, or hopefully something cooler than that, that would basically be something for everyone who's not going into Naxxramas. So they would see the impact without having to actually go in. [In other words, get ready for undead to pop up in some unlikely places.]