Today the WSUS with SP1 package was published to the MU servers and is available for synchronization to WSUS servers! Released to the Microsoft Download Center last week, as of today the WSUS with SP1 package is also available via WSUS.
Released as a full product package, at approximately 160MBs, the package will either upgrade an existing WSUS system to SP1, or on a new system, install both WSUS and SP1.
The WSUS service pack 1 includes support for Microsoft SQL Server 2005 and the forthcoming Microsoft Windows Vista operating system, and provides additional stability and performance improvements.
For more information about WSUS SP1, and to find out more about how to update computers running Windows Vista Beta 2, see the WSUS product pages here.