Audio : Podcast
Audio podcasts (.m4a) can be shared to iTunes U and are created and published from Garage Band. iTunes U, short for iTunes University is a part of the Apple iTunes store specifically for managing, distributing, and controlling access to educational audio and video content for students within a college or university as well as the broader Internet.
Standard format: A .m4a with stereo audio, a 128 k/bits data rate and 48kHz frequency.
Tutorial: Creating a podcast in Garageband 09
Tutorial: Upload to iTunes U