More and more professors -- hell, entire departments -- are banning laptops from their classrooms. Now the business world's doing it too, since people in meetings are using their laptops for the same reason, and in the same way, most students are using theirs:
[Meetings] can be quite a pain  for many people involved. They can get pretty boring, so the participants start to lose interest. As a result, many people have started bringing their laptops into these meetings, presumably to entertain themselves... [Companies] are starting to crack down on the practice [because] most people are watching YouTube videos and posting comments on Facebook walls...
Along these lines, it's a good moment to remember Joseph Weizenbaum, an MIT professor who died recently. His New York Times  obituary notes that, although an important innovator in computer programming, Weizenbaum grew to regret the effects of screen-dependency:
[Weizenbaum] came to believe that an obsessive reliance on technology was indicative of a moral failing in society. [In one of this books, he wrote a] passionate criticism of systems that substituted automated decision-making for the human mind. [He argued that] computing served as a conservative force in society, by propping up bureaucracies as well as by redefining the world in a reductionist sense, by restricting the potential of human relationships.
Weizenbaum anticipated the lights-out classroom, where kindly PowerPointers shed valium rays over children adrift among their own images. In the tradition of Huxley's Brave New World, Weizenbaum saw the way in which much of the technology he'd had a hand in would play into our infantile preference to be left alone, to blot out the world, to have nothing asked of us. These impulses are shared among professors, students, and business people, and if the technology's there to indulge them, many will use it.