Keep in mind that Blizzard didn't announce it because the release can still be postponed, but as far as I know the target release date for Cataclysm is the first week of November (that would be November 2, if you like numbers). The first part of the Cataclysm prologue started exactly 8 weeks before that and the next part of the pre-Cataclysm event will probably happen in 2 or 4 weeks depending on their schedule.
Cant wait!