updated 12:10 pm EST, Thu January 19, 2012
Also likely supports iTunes U app
Following its announcements of iBooks 2 and the iTunes U app, Apple has released iTunes 10.5.3. The update is a relatively minor one, explicitly intended to support the new interactive textbooks made possible by iBooks 2. It may also provide a backend for iTunes U, since the latter app supports buying and downloading online course material.
The v10.5.3 update should be available through Apple's Software Update service, but is also available directly via its website. Mac users must have OS X 10.5 or later, while Windows users must be running at least Windows XP SP2.