WinHEC Longhorn Build
According to Neowin, a new build of Longhorn will be released at WinHEC next week, build 4074. There are only a few screenshots on Neowin, so there's no way to tell if it contains some of the features that 4051 was missing. I'm hoping that this build will become available on MSDN in the next few weeks and that it will play nice with the recent Whidbey release.