As ever, Scott Guthrie has the most comprehensive announcement blog about Visual Studio 2008 and .NET Framework 3.5 Service Pack 1 Beta but this is no ordinary service pack, this is a service pack packed [sic] with new features as well as fixes. For instance, there are major additions to WPF, IntelliSense support for ASP developers (yes, you read that right, ASP developers) and lots of new features for ASP.NET and AJAX developers. Brad's blog has lots of pictures of the new stuff but be warned - this is still in beta so usual caveats apply.
And whilst you try to digest that little lot, the legendary Roger Jennings talks in some depth about Visual Studio futures in VS 2008: The Road Ahead. Amongst other things it looks like we may be filling out the musical scale by elevating F# to a tier one language in Visual Studio with an eye to making the most of Parallel FX, PLINQ etc (looks like I need to commission that new dual quad core machine of mine :-) ).
And if you are still trying to play catch up with what Visual Studio 2008 is all about you can read Rogers' roundup and then read his description of the features that weren't included.