We have received a lot of questions lately about how to authenticate calls to an ADO.NET Data Service.  Mike Taulty has created a nice post outlining some of the options for authenticating calls to data services.  Check it out here: https://mtaulty.com/CommunityServer/blogs/mike_taultys_blog/archive/2008/05/27/10447.aspx

-Mike Flasko

ADO.NET Data Services Framework, Program Manager