Just in case mine is the only blog you subscribe to, SP for the MS developer platform is out now.
Read all about it in the following links:
Soma provides an overview: http://blogs.msdn.com/somasegar/archive/2008/08/11/service-pack-1-for-vs-2008-and-net-fx-3-5-released.aspx
Brian Harry provides some details on SP1 + TFS 2008: http://blogs.msdn.com/bharry/archive/2008/08/11/vs-vsts-tfs-net-3-5-sp1-is-shipping.aspx
When I tried to install SP1, it informed me that I had some old pre-beta cruft that would need to be removed before I could install SP1. In the past, this would mean wasting time hunting around and removing this stuff manually. Thankfully the SP1 installer provides a link to the VS 2008 Service Pack Preparation Tool which does the job. It took about 30 mins to silently do its job and now my SP1 install in underway. I think this is very nice huge improvement in the SP install experience.
UPDATE: .NET 3.5 Training Kit: http://www.microsoft.com/downloads/details.aspx?FamilyID=355c80e9-fde0-4812-98b5-8a03f5874e96&displaylang=en
UPDATE [8/15/2008]: Scott Hanselman's take: http://www.hanselman.com/blog/HiddenGemsNotTheSameOld35SP1Post.aspx