The new iTunes U App and iTunes U Courses format are specifically designed to take advantage of iOS devices (iPad, iPhone, iPod touch) to teach a FULL course utilizing those mobile devices. The platform allows for the easy integration of digital books, Apps, and other materials from the iTunes Store and the web into courses. While public courses are available on desktop computers (both Mac and PC) the whole iTunes U Course experience is best on iOS Devices. You can read about the features of iTunes U Courses at www.itunesu.com.
Previously, content on iTunes U was essentially podcast feeds. This format is still available and is known as iTunes U Collections. But, being that they are simply RSS feeds, they only support the delivery of audio, video, and PDF files.