I think the iPad may be a lightning rod, a highly polemical statement that's going to create a lot of serious disdain from the computing world.
As someone else here said, it's arguably the first truly "personal" computer (though a bit more security would be good
). It's also a true "consumer" computer device. While Macs create content, the i* products are almost strictly about consuming content. So we now have a clear delineation of them (well, it was true before, but the iPad makes it more salient) and we have the first personal size media consumer device/appliance. It's not so much between the iPhone and the MacBook as it is between the iPhone and the TV.
It is of course more interactive than a TV, and I don't think Apple is (yet) interested in TVs, not until they're more interactive/multimedia social devices. I can see that eventually coming down the pipe if all this content on TV and internet can be married. I think that hurdle is going to be the hardest for Apple, which doesn't quite seem to know how to really take advantage of social media or create it.