We had the wiki up for a long time, it didn't get used much. We took it down and people complained a bit. After a while we relaunched it, with a whole new fancy system and a bunch of mods. It didn't work again. In our experience, people here just aren't interested in writing content in a large enough volume for a wiki to make sense. There's like 3 or 4 people who write up content for the wiki, and they write up ALL the content on the wiki, and it's not really fair to them. People do like writing their own guides for random stuff and putting their name on it though, and the number of guides people post goes to back that up. Just look at the number of how to make a map guides in the mapping forums alone. I think making existing guides on the forum more accessible could be a lot more successful.
Good luck with your wiki.