Fast Company and Gizmodo have posts today about Penguin's new interactive books for the iPad. And both posts contain the requisite "sure, these look cool, but come on, are they really books?" comment. To them I say: YES.
Books are complete, static works, tied to when they were written — as opposed to web sites, constantly in flux.
On a side note, if I never see another badly animated disembodied hand in an iPad demo again, it will be too soon.