Politian has posted a lot of samples on using the new ADO.NET Data Services features in ASP.NET AJAX Preview 4 (in fact, at the time of this posting, the entire blog is dedicated to Preview 4!). He walks through some basic scenarios, but then goes into detail about interesting sample topics as he builds his MIX Presenter Application. Highlights thus far:
Keep up the great work Politian! Remember that you can get ASP.NET AJAX 4.0 Preview 4 on Codeplex.