Speculation thereof here:
Before everyone gets in a huff, let’s consider Amazon’s intentions with these patent applications. Surely they would never allow advertisements to be placed in books which you have purchased legitimately at full price, so let’s put that out of our heads. But what if you could take a few bucks off the cover price at the cost of a few contextual ads relating (if possible) to the book’s content? Personally, I wouldn’t mind — partially because I don’t use a Kindle or intend to any time soon, but more because it’s a no-lose situation. Amazon wouldn’t risk alienating its loyal Kindle base with dirty tricks like this, so it’s safe to assume it’ll be at least somewhat opt-in.
An abundance of free or reduced-price content would widen the appeal of the reader — I imagine many people are put off e-books by the idea that they are not getting their money’s worth. As offensive as the idea of inserting ads into a book is to me (and surely to the average reader), it’s almost certainly part of a value proposition which increases the utility of these expensive little buggers.
Of course, there are a lot of precedents for advertisements in books. That said, I think I’d rather pay full price.