If you've been following ObjectSpaces since it was publicly acknowledge who-knows-how-long-ago, this won't surprise you: It looks like ObjectSpaces won't ship until the Longhorn time frame. Mike Gunderloy shares his thoughts and links to a Jesse Ezell post with much more information.
Jesse Ezell is among those covering the removal of ObjectSpaces from Visual Studio .NET, its merge with WinFS, and its slip to the Longhorn timeframe; his entry is worth reading because several object/relational mapper (ORM) vendors post their comments as well. ObjectSpaces was announced as a Microsoft technology back in 2001, so it can now be added to the long list of things (including WinFS itself) that were promised and then not delivered anywhere near on the time scale that Microsoft led people to believe. Whether this is just a continuation of the FUD policy that once served them so well, or continued inability to come up with realistic schedules (I incline towards the latter explanation but do not rule out the former), it underlines yet again an important principle: don't base your own ship dates on what Microsoft says will be available.