Microsoft will release (to "business users") Windows Vista, Office 2007 and Exchange 2007 on November 30. This is a first for Microsoft, introducing new versions of their major products simultaneously. The "general release" will happen in January.
 
http://pcworld.com/article/id,127735-c,microsoftoffice/article.html
 
Ballmer has a press conference scheduled for 2 pm PST, presumably to announce this.
 
http://www.microsoft.com/presspass/press/2006/nov06/11-02NewsConferenceMA.mspx