Randall Isenhour just posted a blog entry that links out to a ton of great content on MSDN that his team has published in the last couple of months.

http://blogs.msdn.com/randalli/archive/2007/07/11/tons-of-new-sharepoint-now-content-live-on-msdn-july-11-2007.aspx

You should expect a new SDK release on the Microsoft Download Center in the next 6 weeks!