GrowYourWiki has a pair of posts on the Pitfalls and Keys to Success for Wiki Adoption within your organization. Its a concise summary of key best practices to encourage participation when you deploy a wiki.

Internally, we've faced similar issues, its eerie that his advice that "Meetings are an especially good place to start" describes how, at least the Tech Team, makes the most use of our Intranet Wiki. He also makes the point that you should plan for success, not failure. Too often, we're worried how a few bad actors may post inappropriate content or misuse the tool in some way. The usual reaction to such a risk, is to either not deploy the tool at all, which can be a huge missed opportunity, or to overburden it with controls, reviews, and approval process so that no one is ecouraged to use it.

Managing to the possibility of failure, not success – If you are more focused on how the wiki will fail, instead of how it will succeed, you have already written your destiny.

HT: Sage advice on wiki adoption: keys to success