I'm in Redmond for the TechBeta Tour, and Paul Donnelly just let one of the testers flip bit on Windows Vista RC2 (5744). Connect members can download it immediately... the public release will be available shortly.
As has already been said, this is the last public build of Vista. After this, Microsoft is changing the Product Keys, and will be checking in some User Experience code that they've been sitting on so they can still surprise the market. Jim talked about this during my interview, and I'll post more on that later.