Available now, at least in the U.S. Apple App Store
Apparently just waiting for Apple App Store approval; check the full post for more details including pricing options. I look forward to exploring, and will share more, er, notes, as I learn more about it
Today, just in time for the holidays, we’re releasing OneNote 1.3 for iOS. Since the launch of OneNote for iPhone nearly a year ago, a recurring request from our customers has been for a version that can be used more easily on the iPad's larger screen. We're happy to announce that today's new release of OneNote for iOS devices includes a version that's tailored for the iPad.