With the release of Vista, Microsoft has produced a document entitled Windows Vista Product Guide. The Guide is 316 pages of details on what is in the released version of Vista. You can download this either in docx or xps format.
But a word of warning: the document is HUGE - the word DOCX file is 61.3MB. IIRC, that's around 2/3 of the size of the I386 folder of Windows NT 3.1. :-)