Dino Esposito has written a nice introduction to ObjectSpaces over on MSDN.  For those who don't know, ObjectSpaces is, to me at least, one of the more exciting features of Whidbey.  It's an object <-> RDBMS mappings system that takes most of the hard work out of mapping from business objects to a relational database.  As anyone who has ever tried to code one of these mappings by hand knows, its not child's play.  Dino provides a nice overview of the current state of ObjectSpaces and has a few basic samples showing the basic features.