Visual Studio 2008 SP1 is here and can be downloaded. Details of the downloads are here, and information on what SP1 brings is here. The big items for me are the Entity Framework and the performance improvements in LINQ.
However, before you go rushing off to install SP1 there are some caveats. If you’ve been running the beta Martin Hinshelwood has some advice and has also run in to problems running the Team Foundation Server SP1 install too.
Once you’ve installed the Service Pack you might want to download the Enhancements Training Kit in order to learn what’s new.