The price is not that important.  In a wealthy western nation, $100 for a textbook is quite reasonable, if you're spending any amount of time reading it.  Compare that to the price of a lecture.<p>Ebooks mainly give incremental improvements.  The one big improvement is searchability.  I suppose search on Google books now suffices.<p>Even if we count that, the benefit of e-books is marginal.  Getting incremental patches is nice in certain fields -- those that change a lot over a decade.  The patching of errata is generally useful though.  Having comments on textbooks would be, well, I don't know if that would be useful.  That sort of thing tends to produce a lot of pedantic comments or other comments on stuff the reader shouldn't be distracted by.  Consider the comments on the PHP documentation.  So much of it is wrong.  It's the sort of thing that would require moderation, so I suppose reader-&#62;author communication would be the path.  But what author wants to spend time on that?<p>Also, it's better for communities to develop around a piece of subject matter than a particular ebook sold in a particular format -- these can include different textbooks at the same time, can include people who get dead-tree textbooks, and can include discussion that extends beyond what textbooks talk about.  It doesn't really make sense for a textbook to come with a forum attached.<p>I think the trouble with all these ideas is that they all worsen the signal-to-noise ratio.  The nicest part about e-book textbooks is the low price and open market.  Looking back at my past, it seems the biggest inefficiency in my learning was in deciding what to learn, not how I learned it.  I think that problem should be what we want to tackle the most (and $9.99 might help quite a bit there, since people can then get a cheap taste of the material).