In education, we often run into objections to wiki-based content because of the potential for objectionable content. This kind of problem mostly stems from spam, and you don’t have to spend much time in wikis to see some pretty awful (and juvenile) examples of this.
We’ve wrestled with this problem a fair amount with our kids open dictionary project. We want this to be a mass collaboration project, but know that if there are instances of obscenities or other inappropriate content, it won’t be usable by schools.
Our solution is to separate the building — which will be done in a wiki — from the final version — which will be in a variety of “frozen” formats (ebooks, uneditable web pages, print, etc.). While the approach may sacrifice a bit in terms of ongoing updates (which still could be submitted by admins or emailed to admins by others), the upside, in terms of being able to ensure quality content while minimizing maintenance work, is high.
I think this is a good solution that many other wikis might find useful.