ObjectSpaces is an interesting addition to the next version of ADO.NET for Whidbey. Jim Webber (his blog is coming soon and hopefully he'll help in improving my "pblog" engine... I hope he gets the hint!!!) and I started a project which we called the "DatabaseTier" long time ago. I still have the C# source code for that (last modified in March 2001). We wanted to provide the same object-based abstraction as ObjectSpaces for an SQL database. Unfortunately, we didn't finish it as with so many things we've started 🙁
I found the link from Konstantinos' blog: K# blog.