Microsoft has migrated its interop discussion forum to a new forum engine.  Find it at:

http://forums.community.microsoft.com/en-US/interopconversations/threads/

There you can ask questions on Vista print drivers, .Docx interop, Web services interop, .NET-to-Java interop, Mainframe interop, VPN interop, and many many other topics. Though I don't believe there is a guaranteed level of service (in terms of time-to-respond), there's a team of people dedicated to monitoring these forums and answering questions or getting questions to the people who can answer them. 

Worth a look if you have interop questions.