Yesterday, Visual Studio 2008 SP1 and .NET 3.5 SP1 released. And as I've been saying, there is a lot in there. ASP.NET Dynamic Data, AJAX enhancements, URL routing (used by ASP.NET MVC in a later release), Entity Framework, ADO.NET Data Services, WCF enhancements including REST additions, WPF Enhancements, ClickOnce/Smart Client enhancements, SQL Client enhancements for SQL Server 2008, etc. Also see the list of changes and fixed issues here.
So, how do you prepare to take advantage of these enhancements? You download and work through the .NET 3.5 Enhancements Training Kit. Jonathan Carter has the scoop on this, so check out his backgrounder. The kit has labs, demo's, presentations, and even suggested agendas for 1-day or 2-day training. So, you could do this individually, or lead a session at work, or volunteer to lead a training day in conjunction with your local user group.
Also note that there is a Silverlight Tools Beta 2 update for VS2008 SP1.