Next month we'll have Silverlight 4.0 RTM'ed, are you going to support WCF RIA Services? http://blogs.msdn.com/deepm/archive...-hoster-and-want-to-support-ria-services.aspx
WCF RIA services should be supported now. You simply have to upload the components and assemblies to the applications Bin directory.
Haven't tried yet, but having those components already installed in GAC will simplify WCF RIA Services enabled applications.