All apple needs to do is add ebooks to the iTunes store and put an ebook reader app on the iPhone in their next firmware update. And watch as the kindle disappears.
Since ebooks are so small in size they could allow wireless downloads similar to kindle. iPhone screen looks so good that kindle will struggle to convince people to buy it.
This could be the easiest way for apple to take over a segment. All they need to do is makes some changes to their software and they will have the ebook segment.
This could also help them sell more iPod touch's.