THis could be a good idea, but you would need to place some restrictions on who can edit what.
If you created a wiki-like message board, maybe it would be intellegent to have the comments be approved by moderators (or even yourself). This way, it will stop idiots from putting irrelevant things on your messageboard that has absolutely nothing to do with the topic being discussed.
I think you might be onto something good, but for now, i'd stay stick with message boards.