I have this couple of requirements for the Geo Desk that requires Authenticating Silverlight Users with Umbraco Members . Some suggest to use  PageMethods  but since I'm using umbraco which I believe  I  cannot access Page Object & hook this Page Methods , I guess "PageMethods" is not the best  fit solutions.

What I did is I create WCF services and added aspNetCompatibilityEnabled setting on the web Config. 

Web Config 

   <serviceHostingEnvironment aspNetCompatibilityEnabled="true" />
 

WCF

      Member m = Member.GetMemberFromLoginNameAndPassword(Username, Password);
            if (m != null)
            {
                Member.AddMemberToCache(m, true, new TimeSpan(2, 0, 0));
            }

To all the Dev Nuts out there,   I would like to hear your experience on  silverlight authentication