Seems all opinions and little in the way of facts. Of course it's all guesses right now. I liked his jump to 'it probably never existed'.
I'm sure Apple has been researching one since their purchase of Fingerworks. That technology has gone into the iPod touch, iPhone and the new touch pads. Microsoft has shown that software is as important, or probably more-so than the hardware. I'm still not sure Apple is even there yet, although they may have done a lot of development that isn't visible yet. The iPhone OS seems closer, but I don't think Apple would put it on a larger device. Hardware is still an issue with Apple's obsession with lightweight and size. (One I agree with). Battery life is important which may be one thing pushing it back, as well as price.
I still think we'll see a tablet like device in the future. There is a new market available. The iPhone is too small, and a laptop isn't mobile enough.