Visual Studio Service Pack 1 and Microsoft .NET Framework 3.5 Service Pack 1 have been released today. The downloads are available here:
"The .NET Framework 3.5 SP1 includes a lot of improvements and
especially TONS (literally tons) of performance improvements for WPF
applications, ADO.NET Entity Framework, ASP.NET Dynamic Data, ADO.NET Data Services Framework and much more…
PLEASE NOTE: If develop Silverlight apps with Visual Studio, please note that after installing Visual Studio 2008 SP1 you must update the Silverlight Tools (more info and download links are available here)." (via MSDN blogs - pblog)