The iTunes U release cycle is long - too long, I would argue - but it does tend to bring good results when releases do arrive. iTunes U 2.0 brought us Course Manager on iPad. iTunes U 3.0 brings us a whole new document submission and grading workflow that is easily as good as anything that currently exists.

Good overview of iTunes U 3.0 by Fraser Speirs (who knows a thing or two about iPads in the classroom).