Yes, we really need some kind of "hypertext" that allows an expression of "hyperlinks" between concepts so that a reader can follow conceptual paths through a c

Yes, we really need some kind of "hypertext" that allows an expression of "hyperlinks" between concepts so that a reader can follow conceptual paths through a corpus of text at will :) I agree with you wholeheartedly, actually. It has been disappointing that the advances in electronic textbooks have, as you say, given us the equivalent of scanned-in copies of the old textbooks, but with some embedded encarta video clips. The main problem, as efforts with XML and microdata and the semantic web (etc, etc) have taught us, is that this (parsing structure, displaying it, and allowing manipulation of that display) is really hard to solve in the general case, and even solutions that get you only part of the way may be so onerous that no one wants to actually author content at that point. There are a few startups that are instead trying to solve this by producing great textbook content on a case-by-case basis, really thinking about what it means to try to transmit knowledge in a totally different medium. I think there is a huge opportunity there, so I'm hopeful that we'll see some really great innovation in that UI/UX space soon.