"From a utility point of view, charging more for the Kindle version seems quite reasonable considering that Kindle books are delivered instantly and for free, that they take up no additional space or weight, that they can be read on any computer, and that they come with handy bookmarks and highlights of what other readers find interesting."

MIND-blowing. I've been an irrational "GREEDY PUBLISHERS! BOO!" guy for as long as I can remember, but if you spin it around, you're getting all of these advantages over physical books for roughly the same price.