Microsoft Vista Event - New York Times

Looks like the release (to business) date is now clear. 

I've been using Vista and Office 2007 on my primary work PC this week and haven't experienced a single crash, application incompatibility, or random weirdness. 

Microsoft plans to observe the release of Windows Vista and Office 2007 to corporate customers on Nov. 30 with an event in New York.

The software maker announced the event — and the release date — in an invitation to journalists yesterday. A third Microsoft program, Exchange Server 2007, a messaging and collaboration product, will be released as well.

Source: Microsoft Vista Event - New York Times