Apple has released an updated version of iTunes 10.5.3 for both platforms Mac
and windows.The new updated version of iTunes 10.5.3 brings many bug fixes ,performance improvement and textbook syncing feature.
The complete change log for iTunes 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.
For information on the security content of this update, please visit: support.apple.com/kb/HT1222