iOS 9.3 is coming in the Spring and will introduce Night Shift as well as a number of other new features.
iBooks and iTunes U Updated With iOS 7 Redesigns
Other than the new design, the apps do not appear to have gained any new features.
What's New in iBooks Version 3.2
iBooks has been updated with a beautiful new design for iOS 7.
What's New in iTunes U Version 1.4
This version of iTunes U has been updated for iOS 7 with an all-new look and feel.
iBooks and iTunes U are free downloads for the iPhone and iPad. [Direct Links: iBooks, iTunes U]