For the latest Silverlight 4.0. the WCF client runtime supports two Message Encodings, the mtomMessageEncoding encoding is not available yet.
So from the client side (browser side) prospective, the Siliverlight APP communicate with the WCF service(.svc) either using the Soap/Text Format or Soap/Binary Format. typically, you can tell this from the Content-Type Header.
here is the binaryencoding.
If you browse the .svc url directly. you may be able to see the wsdl ( if you enabled the servermetadata httpget already)
always, you don’t want end user to view this information directly. hope the user will get a customer error or even 404 error. How to do that?
then when user try to access the .svc directly, will get 404 error as we expect.