http://www.mmo-champion.com/content/...-XP-Blue-Posts
This is not from Blizzard, but the guy who runs mmo-champion.

So, when is the release of Cataclysm?
Now that Patch 4.0.1 is on PTR, I get a lot of mails asking for a release date and I guess I can answer that without too much risk now.

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.

You got your answer, and hopefully people won't yell at me if something goes wrong.
Hopefully he's right...