Today a new update for iTunes has been released. The new release is 10.5.3.
iTunes 10.5.3 allows you to sync interactive iBooks textbooks to your iPad. These Multi-Touch textbooks are available for purchase from the iTunes Store on your Mac or from the iBookstore included with iBooks 2 on your iPad.
iBooks textbooks are created with iBooks Author — now available as a free download on the Mac App Store.