Interesting question. Trying to envision what this would look like, the first thing that comes to mind is Yahoo Answers. Imagine a question like “What was the War of 1812?” followed by a slew of answers, each with their own take on the war, where the community then votes for their favorite replies. Instead of a single source of truth, you could end up with a handful of the most popular “truths”.

What Wikipedia provides that Y! Answers doesn’t though, is the collaborative aspect, where multiple authors can revise the same article. Maybe in this case, we take a page from the open source model of software development, where an author can submit a “revision” to an “answer” (like submitting a patch), which the author can then choose to accept or reject. If the author rejects it, the submitter can instead choose to “fork” the original answer. Just brainstorming here, but maybe it will trigger something. :)