Just to clarify we have had huge success with tablets for teachers, but have so far found little use for them with students.
We have trialled it with the SEN students so far with mixed feedback.
Teachers on the other hand love them. I think the killer apps are Registration, Presentations, and using the webcam to display things on the board. Most of the benifits come from speed of boot and reliability of it just working in the classroom. Just as an example I've never had a teacher phone me and say it wasn't working on the projector.