I started thinking about this today. Successful song writing partnerships stretch back to Lennon/McCartney and I'm sure much further (Rodgers/Hammerstein comes to mind) but I can't think of any composing partnerships. For instance, Mozart and Haydn getting together to work on a symphony...Does "serious" composition preclude any such "nonsense"? Beyond a two person partnership however, I was thinking of "open source" composition, in the sense that Wikipedia is open source. Of course, Wikipedia hasn't done that well at producing high quality output. Would it all be doomed to failure? And of course there would have to be some sort of frame, boundaries, parameters, whoever set those may be considered the "composer proper", although that role could in theory be filled by a group as well.
Does anyone know of any examples of successful open source compositions, or has anyone been involved in such a project? I don't mean free improvisation or jazz, they are in the moment arts. I am speaking of a group planned project, like the open source movies and such.