I don't think it "another story", I think it cuts to the heart of the question. What constitutes a business? It is merely the functional aspects? Or is it (as I believe) inherently tied to the larger vision?

To me it's the latter. Successful startups are built at the junction of motivation, skill, and vision. Zuckerberg, as far as I can tell, had the first two... but the third was certainly influenced (if not outright stolen) by his interaction with ConnectU. The twins made a tremendous contribution to Facebook, and were rewarded by (as far as I can tell) fraud on the part of Zuckerberg.

That's most definitely worthy of compensation. I still think they sold out for far too little really.