Btw, if you can get to Brussels at the end of the month, Kaveh B will be at the www.libregraphicsmeeting.org so you could chat to him about it there :)

Not gonna be in Europe this spring :P

2 cents from a XeTeX enthusiast: I was amazed at how fast the iPhone is at re-rendering the whole document everytime he flipped it by 90° and back. Definitely promising.

I don't quite understand yet what his plans are in terms of licensing. I doubt that with this technique, publishers will sell their ebooks as plain TeX files. Or did I miss something? Like a form of encryption?

(Though plain TeX/XML would be a dream. My only experience with a technical ebook – a physics textbook – was a restrictive, flash-based DRM annoyance worth not a single penny).

Another thing: the fact that TeX itself is very lean (unlike InDesign & Co.) is due to its character as a simple macro language. As soon as you add so-called "packages"*, you can see your TeX/eTeX/LaTeX/XeTeX system (some standard distributions with differing inbuilt functionality) quickly grow to occupy a couple hundred MB. While most of this sure is overkill for simple book typesetting – after all, we're just going for textbooks – there would have to be some sort of standard defining which TeX version and which macros come on the iPhone, and which code has to be packaged with the book. (Or did I miss something again?)

* code modules to enable things as simple as tables spreading over multiple pages