My kids' high school ( http://knoxcountystemac.knoxschools.org/ ) has done this as well. I'm still not sure how I feel about it. On the one hand, the kids aren't hauling 30 pounds of books to and from school everyday, school lockers are pretty much superfluous, and the iPad is a great tool. On the other hand, it's very hard for me as their parent to tell (at a glance) whether or not the kids are actually doing school…
Do they use it for reading, or also for tests? I'm really curious about the testing they demonstrate in the video, because it seems inherently rigid and less indicative of a student's understanding than writing something down. Do they write all their tests on iPads, and are the tests multiple choice, or short-answer?
I believe it varies with the teacher and the subject though.