It is not clear from the download location (the date on the page didn't change) but the latest VM Additions at https://connect.microsoft.com/Downloads/DownloadDetails.aspx?SiteID=151&DownloadID=2202 include support for Vista Beta 2.
Others who downloaded Microsoft Virtual Server 2005 Updated Additions also downloaded:
- Microsoft Virtual Server 2005 Management Pack
- Virtual Server Host Clustering Step-by-Step Guide for Virtual Server 2005 R2
- Virtual PC vs. Virtual Server: Comparison of Features and Uses
- Windows Server 2003 Service Pack 1 Administration Tools Pack
- Installing Virtual Server 2005 R2 on Windows Small Business Server 2003 with SP1
The VM Additions for Windows Server 2003 SP1 are here http://www.microsoft.com/downloads/details.aspx?FamilyID=a963433c-193b-41ac-af6e-ab7ab2db8541&DisplayLang=en