What I see as really attractive, though, are the potential commercial and educational benefits.
From the commercial world, anyone who works in a field where important information changes relatively frequently could benefit from having "books" that are updated (possibly via subscription fee) as data changes. Doctors can always have an up-to-date version of the Physician's Desk Reference in the palm of their hand. Software developers and computer technicians can have reference books that aren't out of date practically by the time they come out of the box. And so on.
For education, specifically at the college level, one of the main cost factors for textbooks is the high price of "short run" printing. Going all-electronic can reduce the costs tremenously. Also, students can carry all of their "books" around easily (including books from previous courses, for reference). The likewise can gain the benefits of having their books be made up-to-date as changes are made.
And, I should have added, get the college students used to e-readers for their textbooks, and they’ll be the launching point for widespread adoption for regular commercial use.