You can download the Windows Vista Pre-RC1 Beta version here, limited to the first 100,000 downloads! No registration required, it’s publically available. You’ll have to burn it to DVD to install it, and it’s a big download (2.58GB). My copy is downloading as I write this, but I’m not sure if I’m going to test it out or not. I might get a chance to! Not on a system that matters, of course :-) Thanks to 4sysops.com for the link!
UPDATE: Apparently, according to the Windows Vista Team Blog, the download can only be activated if you install with a key as being an existing beta tester. So…not as nice as it would appear, since they never mention this on the download page!