If nearly all textbooks wind up on Kindle, then paying $400 for a Kindle would turn into almost a no-brainer decision for college students. (A discussion group on Amazon's site seems to make that clear.) A single textbook can cost $150 new -- and still maybe $100 or more used, with the chance that the used book is a different version from the one assigned. If e-book versions cost even 25% less, that's a huge savings when talking about sticker prices that high.
And then there's the sheer convenience of having all those bulky books in one little device. Imagine the back problems the Kindle could prevent.
Textbook publishers should be intrigued. They hate the used book market. It cuts deeply into new book sales and forces them to continually published "revised" versions to force students to buy newer versions. With e-books, students can't easily resell the textbooks, while at the same time publishers could charge less so students have less incentive to buy used books anyway. This could be good for everyone involved -- except the college bookstores.