Actually, this idea has a lot of merit, I think. Even with Ugilick's solution, you'd have to put sneak preview on, and then anyone can look at it still. Plus, they wouldn't be able to see any behind the scenes scripting, which can be really helpful sometimes.
What would be REALLY cool is if they could leave "notes" on your pages that show up when you edit, but are not published with the story. And would solve a few of the drawbacks of coauthoring for editors. I mean, imagine how awesome it would be to just see this:
I'd love it. Its definitely wishful thinking though. Hahaha.