What can we do with the idea of a “book” if we eliminate the limitations of ink and paper, rather than mimic them?

John Gruber, asking a question that seems utterly obvious and yet is seldom if ever confronted. This Push Pop Press he’s talking about sounds like just the thing for a real magazine or deep-content newspaper experience on an iPad or similar device.
Well, except for the “content as app” design. I don’t want an app for each and every book/magazine/paper, and I don’t think anyone else does either. One app to rule them all, please.