As if Wikipedia never shoves banners in your face. I'd rather have the stackoverflow model than the Wikipedia one. As for collaborative, try the edit button on any question or answer. It's already a wiki. If you have enough karma, you can put your words in anyone's mouth; if not, it gets into a review queue. I'm one of the people with enough karma to process that queue, there is very very little abuse actually. You can even submit anonymously, on Wikipedia your IP is then published but on SO I just see "anonymous user". Again, stackoverflow already has the better model. Finally I'd like to add one point to the two comparison points you already mentioned: the Wikipedia syntax is one of a kind, weird and you need to learn it specifically for Wikipedia (and other MediaWikis, but they're not that common that everyone already knows it). Stackoverflow just uses markdown, which as a developer is not something you won't already partially know. Let's not turn it into Wikipedia.