As far as my understanding currently is WCF (Windows Communication Foundation) enables the Silverlight application to communicate with the Web Services on the server. The problem is that the server also has to serve the Silverlight application as well from IIS, so the question is: does IIS treat each Silverlight application as an URL end point or as a reference from an ASP.NET host? From the learning courses on Channel9, I get the impression as it's a reference from a ASP.NET file which I think means no cross site scripting or in other words, as seperate URL end points with their own folders. Though I can easily be wrong...