Url: http://blogs.msdn.com/astoriateam/archive/2008/…

After some discussion, Mike Flasko (Program Manager, ADO.NET Data Services) has clarified the relationship between the Silverlight 2 Beta 2 Data Services Library and the SP1 of VS2008/.NET 3.5.  Specifically he says:

While the Silverlight Beta 2 data services library may work in some scenarios against a .NET Framework 3.5 SP1 RTM server, you should NOT count on the two being fully compatible with each other.

For me, I am going to wait to roll up to SP1 RTM until Silverlight 2 RTM’s.  Caveat emptor. Follow the above link to read his full discussion.