The CEO of Penguin UK just showed off a demonstration of ebooks on the iPad:
The possibilities for children's books are really incredible (but who would let their toddler mess around with a four hundred dollar device?), and the idea of textbooks and science books could be radically changed (for the better) by the iPad.
I do have to wonder, though: The one actual prose book on display here seemed to have a whole bunch of features that covered over the text. The thing that Amazon did extremely well when they created the Kindle was that they identified the need for the reading experience to surpass the bells and whistles on the device. We won't know if books on the iPad—plain, ordinary books with just plain, ordinary text on every page—can be an immersive experience.