As the author of hundreds, if not thousands, of documents, most of which had to have multiple people looking at them, I have to say that this is a great way to get feedback. In the past I'd receive five or more different attachments from people that I'd be forced to wade through to find changes and edit suggestions. This also brought back memories of ancient comp and fiction writing classes where we actually had to go to Kinko's, make 20 or more copies of our essay/story/whatever, staple them and hand them to our class members. Had the wheel even been invented yet back then? Online collaboration tools would be great in this circumstance as well.
I'm excited about this. I hope I never receive - nor send - another Word attachment again.