The page also says the pre-release ships October 2nd, 2006.
I know it's not always accurate, but seems like we are getting the expansion this year after all, even if delayed.
Id be more inclined to say the game will be released around Christmas from a marketing standpoint. Blizzard will get maximum benefit this way with the holiday shopping season. If thats one thing Blizzard knows how to do right, its marketing their games.
AFAIK when you see a game with a release date of the "2nd" for any month it's an indication that it's a fake release date. EB uses this often I believe...
Really depends what bugs rear is ugly head during the beta test. I doubt Blizzard would release the expansion in a buggy form like some of their patches have been in the past due to the cost that players have to associate with it. I think once some of us get to see how polished the beta is will we have a good indication of when it will be released.