So my tip to PMs out there is to think carefully about what question you want to know the answer to and blog it!
My concern about this tip is that it works great if people read your blog. I, however, see a lot of PM's that want to get this sort of "instant feedback" with unrealistic expectations that all they need to to is start a blog and get that first post out the door. They expect people to flood them with useful feedback on the topic, but that doesn't happen unless you've already established readership or beg-borrowed-stole linkage from well read bloggers.
I think a better way for these folks would be if the Product Feedback Center had a "Question of the day" where each PM can line up to have their burning question asked on the front page of our feedback center and watch the discussion that follows. This way they don't have to keep up a blog and would benefit from all the people that land on the feedback center that already said "I have feedback to share".