Microsoft has released Windows Vista RC1 on Microsoft Connect today. It appears this build is not yet public, but it should be released to testers of Beta 2 within a short period of time. If you have access to Vista through Microsoft Connect you should be able to download it without problems.
As soon as Vista RC1 is released to the public we will update you as soon as possible.
"To the TechBeta community:
It’s official — Windows Vista RC1 is done!
We could not have achieved this milestone without your support. The quantity and quality of feedback and data we received from you has been essential to helping us progress. Thus we wanted you to be the first customers outside of Microsoft to get access to the bits. Next week, a broader set of technical customers will get them via MSDN and TechNet. But you’re the first! We wanted to get it into your hands asap so you can start giving us feedback right away."
Read more at the Vista Team Blog.