Approximately two weeks following the launch of the revamped iTunes 11 application, Apple has released iTunes 11.0.1 via the Mac App Store Software Update tab to users.
This update to the new iTunes addresses an issue where new purchases in iCloud may not appear in your library if iTunes Match is turned on, makes iTunes more responsive when searching a large library, fixes a problem where the AirPlay button may not appear as expected, and adds the ability to display duplicate items within your library.
The update is generally a bug fix release. It includes fixes for items from iCloud not properly appearing in user libraries, an issue with the AirPlay button not appearing, and making libraries with several items more responsive.
Additionally, this new update restores the ability to display duplicate items in user libraries. This was a feature notably lost in the transition from iTunes 10 to iTunes 11. Apple promised these updates earlier this month.
iTunes 11 includes a completely redesigned player, UpNext, a new MiniPlayer, enhanced iCloud integration, a redesigned iTunes Store, and more.