I'm going to buck the trend here and actually comment on this guy's article instead of rehashing all the pontification about the iPad.
I'm not entirely convinced by his 'Formless vs Definite' dialectic. Even a Danielle Steel novel has a degree of form - chapters, text breaks, paragraphs are all primarily visual, rather than textual markers whose form can vary significantly depending on the canvas used. Likewise, 'Definite Content' represents a pretty broad spectrum from the stylised books on design that he shows to a scientific article in which the juxtaposition of image and body text is haphazard.
He's also being more than presumptuous in claiming that the iPad represents any real novelty in this arena. The second part of his article makes me wonder if he's been asleep the past 20 years and missed the big change to scrolled text that's called the world wide web. The fact is that despite our deep familiarity with scroll-bars, we still find comfort in the page as a presentational device.
Apart from these two ideas and a final paean to the idea of nicely-bound books there's not much else in the article. In fact, I have the niggling feeling that he spent more time choosing the fonts and laying out the pictures than deciding what to say.