As Tim O'Reilly says:
Our experience with collaborative editing of book manuscripts at O'Reilly suggests that the amount and quality of participation goes up radically when comments can be interleaved at a paragraph level.
Colaboration and sharing of data is about to take off in new and very powerful directions. I highly recommend you take a few hours, watch the demo video, and dive in to see what the future is going to bring. It's very exciting.