Interesting... but if that's happening in your class, professors, I'd say your class needs to be taught on a more challenging level, and it needs to be apparent that the way things are presented in class will matter for exam purposes.
Now, you might think if students are going to go off task during class that they'd just skip class, but the laptop is a great compromise for the student. You have a complete defense against boredom. If you can go on line, you're able to do what you'd probably be doing if you'd skipped class. And there's the added bonus of putting in an appearance and being able to engage with the class at any point.
Presumably, a good student has learned the rhythms of the less-than-challenging class. He knows how it feels when the prof is drifting into a languor — repeating things, reciting the facts of the case the student already read, riffing on the general themes of the course, amusing himself with stories about some judge he's always fawning over. And this good student can half-listen and reengage when he hears key words and changes in intonation that signal that something useful might be happening.
Profs, don't take the laptop away from the student. Take the student away from the laptop.