Since the e-book format was not born/thought of/included in contracts when many many books were published (well, most, really) - it's not surprising that publishers are moving into this dark territory and looking to make existing backlist titles available in this new format. Read about one such publisher here. According to Jane Friedman, "Electronic 'is going to be the centre of the universe'". It's an interesting insight into current thinking and developments in the world of e-books - not just in the publishing model, but in the use of social media to publicise the e-books.
PS I have not (yet) been offered a Kindle to review. Just in case you wondered...!!