Microsoft has just released the long-awaited SP1 update to Visual Studio 2008 and .Net 3.5 after being in beta for a number of months.
Download it here
SP1 brings loads of enhancements and features to both Visual Studio and .Net 3.5, including a major performance (20%-45%) boost for WPF, the ADO Entity Framework, and full support for the newly released SQL Server 2008.