haha... clearly I don't check out these forums enough to know what has and has not been done before. Never the matter.
As someone suggested... compiling each piece into mp3's and having someone splice them together... WOULD NOT... be difficult... it truly wouldn't. I do it all the time. So long as the next addon sounded similiar to the previous with the same key and tempo. Any artist who cannot make a piece play in a certain key and tempo, would simply be exempt from such a project.
The challenge is making your piece flow with the previous one. And that's just what it is... a challenge. Imagine this collab moving from Classical to techno to rock and to drums and bass in one flowing piece. It can be done, it would simply rely on the artists being able to pick up from where another left off... if this cannot be done... that is unfortunite but I know there is some serious Grade A talent here. I'm willing to do my part... it's a matter of participation.
But again... if this is an unpopular idea... that's fine. I have a dream.... :).
P.S. MaestroSorrow... you have had plenty of time with that collab :P... bout time I heard the results don't you think?