Wiki risks
I've not seen this Channel 9 video yet, but plan to - it's a interview (part 2 of 2) with MSDN team members discussing Korby's baby, the MSDN Wiki:
"Don't know about you people, but I look at community involvement as being a great thing for everybody. However, I'm not the one who has to take responsibility for opening up a site to modifications from the general public. When we see these projects, it's easy to forget the kind of risks that are being taken on behalf of the employees who drive the efforts.
This interview reminded me of what those risks can be."
(Example community content here).