Microsoft is making available Windows Vista pre-RC1 Build 5536 for public download. Although they expect to close the limited test after they reach the 100,000 downloads mark, it's likely quite a few more thousands will slip in before the file is removed.
This is the first Vista build made publicly available by Microsoft since Beta 2. Word is out on the street that the actual RC1 build will be released as soon as a week from now, which makes me believe that at this point Microsoft mostly wants to solidify its Release Candidate by ironing out as many bugs as possible.
This release was previously made available to registered testers receiving positive reviews.