I was just browsing the WCF forum on MSDN. Here's a summary of the recent interesting threads dealing with interop:

• How to map complex data types exposed by a J2EE web services, into a WCF client?
• How to use connect from an AXIS 2 client to a WCF service using SSL?
• How to transfer a Hashtable or Vector over web services?
• How to transfer a Fault from WebLogic/Java to a WCF client
• How to tell svcutil.exe to use existing types when generating proxy classes
• Contract-first design with WCF and the svcutil.exe tool (Generating service stubs)

Check it out.