On Apple’s “iBook” format :
.. we were surprised and delighted by some aspects of the .ibook file that iBooks Author spits out. Their extensions to EPUB are done precisely the right way. They’re not done with dollops of embedded JavaScript — a fact that Baldur Bjarnason laments. (You can be sure EPUB’s governing body, the IDPF, is lamenting that too.)
Instead they’ve done it with microformats.
— via The Book.ish Blog