A few folks have asked me what I have been up to after wrapping up LINQ previews and V1. I have not been able to answer that question satisfactorily because what we were working on was non-public (well almost except the mention of now obsolete name "Alexandria" at PDC 2008).
Few other folks have wondered aloud if I was deaf to their feedback about the importance of multi-tier support in LINQ to SQL (and similar projects). I was not deaf but I couldn't answer that question satisfactorily either.
Now I can answer both by pointing to a real preview; not just blah blah.
Take a look at the .NET RIA Services March 2009 preview. It is intended to:
Personally another satisfying thing is that, now I can answer your questions in a straightforward fashion without worrying about what I am allowed to say.
BTW, in the good tradition of the LINQ project, we also have a great walkthrough in the MSI and a good set of quick starts on the download page.
Don't forget to see Brad's and Nikhil's sessions at MIX - either live or after the fact.
P.S. (Thu 3/19 update): We also have some cool additional code for you. There is a new project template that missed the March 09 preview train by a hair - it makes authentication hookup really simple. Two sample apps make it easier for you to build good looking apps with real data hookup on the server-side. I would urge you to actually go through the walkthrough steps first and not use the newly posted, completed solution ;-)