As it turns out, the Everything engine already has support for wikis, and there are various wikis dotted around the monastery for groups to collaborate on keeping things running smoothly.
There is even a secret wiki on Perlmonks that is open to everyone. You can post anything you like there. But, as I said, it's a secret so if I told you where it was, I'd have to kill you. But seriously, it can be found by searching diligently.
Getting back to your initial question, though, what would you use the wiki for? Just because you build it, doesn't mean they will come. The only thing I can think that might benefit from the wiki approach is some kind of souped-up perldoc tutorial/reference, however, I'm cynical enough to believe that after an initial flurry of activity it would fade away and wither.
Come to YAPC::Europe 2003 in Paris, 23-25 July 2003.