This messsage is from Andrew Conrad, on the ObjectSpaces team:

ObjectSpaces is not participating in Whidbey beta 1, however, it remains 
part of the Whidbey/Yukon wave and will be made available as a downloadable 
add-on pack for the .NET Framework Whidbey shortly after Whidbey ships. 
This additional development and stabilization period will be focused on 
improving the overall ObjectSpaces programming experience and providing 
tighter integration with WinFS, the next generation file system in 
Longhorn. The schedule for the ObjectSpaces mapping tool is also being 
adjusted accordingly.

So not only is Whidbey being delayed, but now ObjectSpaces is delayed beyond that delay. While I like the promise of OS, I think it's time to do some in-depth digging for code that can do more than OS can - and can do it today.