You can get the latest version of iTunes for your Mac by clicking the Apple logo and selecting 'Software Update'. You can download the latest version of iTunes for Windows by clicking the start menu and typing 'Apple Software Update'.
You can also download iTunes by using the link which follows:
The following information is available in the release notes.
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 in the iBooks 2 application on your iPad.
iBooks textbooks are created with iBooks Author – now available as a free download on the Mac App Store.iBooks 2 and iTunes U for iOS along with iBooks Author for the Mac were announced today during a press conference held by Apple at the Guggenheim Museum in New York City. Apple hopes to use it's technologies to help make education more interactive for students.