"Windows Vista Product Guide" can be downloaded from here in either Word format or the original XPS (XML Paper Specification) format, which Microsoft touts as a replacement for Adobe's popular PDF. The latter requires an XPS viewer application to read the guide in Windows XP. (Caveat: The Word document is approximately 60MB in size.)
Although Beta 2 of Windows Vista debuted Tuesday at WinHEC, it's currently available only to IT professionals and developers with MSDN and TechNet subscriptions. The wider distribution of Vista, called Windows Vista Customer Preview Program (CPP), will be opened "in the coming weeks," according to Microsoft statements at WinHEC.
Microsoft anticipates that as many as 2 million will test drive Vista Beta 2 in the CPP.