Read the White Paper (PDF) http://www.microsoft.com/downloads/details.aspx?familyid=090deaf6-2eaa-4aaa-8b3b-2e199db4a97d&displaylang=en

(the SP1 beta is not publicly available yet -- stay tuned for an announcement.)

Also of note: a useful Vista Pilot paper was highlighted in last week’s TechNet Flash and is on TechNet here:
http://technet2.microsoft.com/WindowsVista/en/library/a825cf2a-5248-4aa7-b8f5-
a074339c729c1033.mspx