Open-sourced possibilities

I had an interesting thought the other day. I was thinking about the wikipedia and what a phenom that whole thing is, and it occurred to me that it would be an interesting project to try an open-source screenplay. I'm not exactly sure how the whole thing would work, but I like the idea of an unlimited number of interested people getting in on some core idea. Again, how to set it up is not entirely clear, but the idea bears some consideration.
Lego just built a whole line of toys through an open-source process, and, of course, there's the whole mozilla, linux, and apache successes. Admittedly, these are all totally different fields than what I'm talking about, but again, I think it could work.
I've seen there's some kind of open-source fiction writing going on somewhere out there, but it was just offhanded. I'll have to investigate further, and maybe try and work up a structure or something. Just an thought I thought I'd share.