From Fox News at:
http://www.foxnews.com/story/0,2933,539781,00.html
First, I didn't realize that the Kindle "dominated" the ebook Market. Second, the article doesn't make any mention of the benefits of the electronic ink screen.
But I do agree that many more people are starting to use their phones for reading. The main reason for that, I think, is that people are able to get the content on the phones very easily. Contrast that to the comparatively more difficult process of getting books onto USB-based devices like the Sony Reader, and the exceedingly more difficult of walking into a store and buying a p-book.