My team and I are exploring that possibility right now.

We have come across a few interesting tidbits considering the model:

A concern is that without a way to direct your crowd sourcing (centralized articles) people will be all over the place and the knowledgebase suffers. (kind of along the lines of http://www.nytimes.com/2009/07/19/technology/internet/19unbo...)

A clear plus would be ability to include more view points. A less subtle plus (but a big one) would be that with a voting system, it would elevate some credibility concerns.

Edit: In answering your question directly, there is Knol.google.com which is very similar to what you are suggesting.