I'm downloading the x64 version now from my MS Connect account.
Here's Paul Thurott's post on it.
http://www.winsupersite.com/reviews/winvista_rc1.asp
This little part really caught my eye.
Distributing Windows Vista
As noted above, if you want Windows Vista, you're going to be able to get it. In addition to 20,000 technical beta testers, 500,000 MSDN and TechNet subscribers, and millions of Customer Preview Program (CPP) customers, Microsoft intends to ship RC1 to millions of people from around the world. I can't yet discuss the details of this plan for some reason, but stay tuned: RC1 is going to be quite widely disseminated. I can tell you that RC1 will not time out until the end of May 2007, and that Microsoft will support RC1 with hot-fixes and security patches through the RTM (release to manufacturing) of Windows Vista, currently slated for the second half of October 2006.