We've just released Visual Studio 2008 to manufacturing and the web! MSDN subscribers can go download the bits immediately.
I've already been seeing questions from folks about when a compatible version of the Visual Studio SDK will be available. The bad news is, not quite yet. The good news is that we think we have the final build, and plan on posting it to the web later this week after some final testing. I'll be sure to post here as soon as the bits are live for download, so stay tuned.
As a reminder, the August 2007 CTP of the Visual Studio 2008 SDK is not compatibile with the release version of Visual Studio 2008.