Generally good advice here. I'd like to add:
- You really need a champion - someone pushing this to developers and management (without being pushy - that's a challenge!) and providing support & tutorials when possible. This person also needs to be a peer (so a fellow developer, not someone in a remote IT department) and really customer focused i.e. ready to make changes when requested.
- Speaking of changes, some people here say wikis are unstructured. I disagree. Our MediaWiki installation is structured using categories, particularly with two extensions:WarnNoCategories (to require users to add a category when saving a page) and CategoryTree to show how all the categories fit together (this can be linked to from the sidebar). I've got more tips on how we keep this low threshold, if you're interested.