At the same time, Marshall McLuhan wasn't blowing smoke when he said the medium is the message. There is something different about a page of ink on paper and a "page" on an electronic screen, even if the screen does a pretty nice job of simulating ink on paper. It will be interesting to see how the electronic book and the physical book influence each other in the next few years, as information technology continues to advance. For one thing, I expect that the potential for augmented audio-visual content won't be the province of the electronic book alone. With smaller and smaller microchips, why shouldn't the physical book also take advantage of sounds and images in new ways?
Of course, it will also be an interesting challenge, and it should be fun, for us editors to help authors take advantage of these capabilities as they evolve.