WCF might use the WS-* SOAP standard for communications but the WS-* specs leave vendors with a lot op maneuvering room when it comes to how to exactly implement things. As a result doing interoperable work between WCF and, for example, an IBM WebSphere server can be quite tricky to setup. Something I have experienced all to often
Fortunately Microsoft has now released the WCF Express Interop Bindings that should make live quite a bit easier. These binding are preconfigured for a number of common platforms like Apache, IBM WebSphere or Oracle WebLogic and should make things quite a bit easier. If only I could have used these several years ago, but you can now
You can download them from CodePlex here.