On the Channel 9 web site I saw today that Microsoft released the Service Pack 1 for Visual Studio 2008 (and Express Editions), .NET 3.5 and TFS 2008. This also means there is a WPF 3.5 Service Pack.
You can find more information about what's new in TFS 2008 SP1 here. It seems that especially the source control got some major improvements. There are also some very interesting performance improvements. And, it supports now SQL 2008.
Here are the download links.
Visual Studio 2008 Service Pack 1 (Beta) .NET Framework 3.5 Service Pack 1 (Beta) Visual Studio 2008 Express Editions SP1 (Beta) Visual Studio 2008 Team Foundation Server 2008 SP1 (Beta)
Update #1: Scott Guthrie posted on his blog more information.
Update #2: Christian Weyer writes about what's new in WCF 3.5 SP1 and Omri Gazitt writes also about the WCF 3.5 SP1 enhancements. It's interesting to read that Data Services (previously known as Project Astoria) is now included in WCF.