Just logged in to MSDN and saw that Vista has been posted for download. RC1 build 5600 is available for x86 in English, Japanese, German, French, Spanish, and Arabic. There is an x64 English build as well. Enjoy and please provide feedback if you run into any issues.
From the Windows Server Division Weblog, the August CTP of Longhorn is available on MSDN. They say the build doesn't include new features over Beta 2 but does include a lot of the core OS fixes, performance, and stability improvements coming from Vista development.
Sorry I haven't posted in a while, I've been extremely busy on a really great project. I'll be posting at length on that in the near future. For this post, I just wanted to point you to an article over on the Exchange team's blog about processor an memory considerations for Exchange 2007. I'm currently implementing Beta2 for the project mentioned above so this is very timely information. With all the talk of Vista and Office, Exchange is somewhat under the radar right now but this is a very significant release.
Mark now has a blog at http://blogs.technet.com/markrussinovich/ and starts out with a typically detailed post on process startup delays.