Abilene Christian has started a new program in which every student is given either an iPhone or an iPod Touch. (Those with iPhones have to foot the bill for their own service plans.) ACU supplies custom web apps that can be used with these handheld devices. Students can access campus maps and data in the cloud as well as class schedules, calendars, and so forth. They're a lot cheaper than laptops, and battery life is better (once you turn off 3G and rely on the campus wifi).
Obviously mobile devices are not substitutes for laptops or desktops ... yet.