Phani recently posted part 2 of his two part series on using the ADO.NET Data Services v1.5 CTP2 Silverlight client library in xdomain and out-of-browser scenarios.  You can find both posts here:

Part 1: Using the ADO.NET Data Services Silverlight client in x-domain and out of browser scenarios – I

Part 2: Using the ADO.NET Data Services Silverlight client library in x-domain and out of browser scenarios – II (Forms Authentication)

-Mike Flasko

ADO.NET Data Services, Program Manager