Why do I hear.....

[MongoJerry]

40 'servers' is probably a much bigger number of hardware machines.

I definitely know that Kalimdor and the Eastern Kingdoms are on seperate servers. In addition, instances seem to be on seperate servers of their own, since it was common in the beta to be playing just fine in instances while the outside world was crashing.

Also, somehow different subsections of the world may be on different machines -- at least the cities might be. At least, that was the reason given for why it was difficult to link the auction houses in different cities (back when all cities had auction houses). The claim was that since auction houses weren't in the original spec, they didn't have the architecture drawn up to support it. In other words, they would have to have a seperate auction house server that the city servers linked to. I don't quite understand why this was such a major hurdle, but anyway, it does show that different pieces of the game world are on different servers.

A couple of recent Blizzard posts related to lag and crashing servers:

http://forums.worldofwarcraft.com/thread.a...mp=1#post599926

http://forums.worldofwarcraft.com/thread.a...mp=1#post610161