Apple has released iTunes 11.1, a new version of iTunes with support for iTunes Radio, Genius Shuffle, Podcast Stations and iOS 7 sync support. The new version wasn't available through the Software Update system preference as we checked just now, but is available for download from Apple's web site.
Here's what Apple has to say about the release's new features:
iTunes Radio. iTunes Radio is a great new way to discover music. Choose from over 250 stations or start a new one from your favorite artist or song. Enjoy iTunes Radio ad-free once you subscribe to iTunes Match.
Genius Shuffle. Introducing a magical new way to experience your music library. Choose Genius Shuffle and iTunes instantly plays songs that go great together. Click it again to hear something new—enjoying your music has never been this easy.
Podcast Stations. You can now create custom stations of your favorite podcasts that update automatically with new episodes. Your stations, subscriptions, and current play position sync over iCloud to the Podcasts app.
Sync with iOS 7. You can now use iTunes to sync your favorite music, movies, and more to devices with iOS 7. In addition, iTunes now makes it even easier to quickly organize and sync apps to your iPhone, iPad, and iPod touch.
If you're not seeing it, refresh periodically - it should update eventually.