The short answer is, just on BizTalk for now. When you post a new topic you can select a category - such as, "Question for the group."
My feeling is that it's hard enough to keep up on what's being posted on one message board let alone multiple message boards with various purposes.
My suggestion: choose a descriptive title, like "Wanted: help with Quickbooks" or "For Sale: ink jet printer". I posted a topic this week that I titled, "Recommendation for furnace service company?" and got a couple responses.

