Apple has released a beta version of iTunes 11.1 with support for iTunes Radio, Apple's new Pandora-like music streaming service. The beta has a build number of iTunes 11.1b44.
iTunes Radio is a new internet radio service built into iOS 7, the next version of the Apple TV and the next version of iTunes on Windows and Mac, all expected to be released this fall. The new feature offers music discovery through featured and genre stations provided by Apple or through the creation of new stations based on a specific artist or song.
The service is supported by advertising, though subscribers to Apple's $24.99/year iTunes Match service receive ad-free listening.
iTunes 11.1 Beta 1 is available via Apple's Developer Center, though it's currently only available in the United States.