I like this in principle. You are right that the "working part" of a tablet could be a bit lighter with this approach.<p>However, one of the great benefits of tablets is how easy they are to start working on: with my iPad, if it's in my briefcase and I have to add a calendar item, I can pick it up, start it, add a calendar item, and put it back in mere seconds.<p>Having it attached to a keyboard and having to mess with the wire would slow this process down a bit, I would think. Also, I can't pick up the whole package and run to a meeting quite as easily.
I don't like the wired approach. It reminds me of our first VCR as a kid that had a wired remote. lol<p>I'm sure others are doing it too but I think that Asus has it right with the Transformer line. You have a tablet that is self contained. But you can easily attach the keyboard which then turns it into a laptop. The keyboard has some additional I/O and another battery. I wonder if it would be possible to take that one step further and have additional cpu/gpu power in the keyboard so that as a laptop it is even more powerful.