As a current college student, I use my laptop (OneNote ftw) often for note taking. However, during a really boring class, even I'll start surfing the web. I notice a lot of students playing games, watching movies, doing online shopping, etc.
However, instead of just banning laptops, there's a lot that the professors and university can do to make students want to pay attention. First off, Powerpoint has ruined the university lecture. Most textbooks will come with companion slidesets for each chapter, so often a professor will just throw those up on the board and reiterate the same content TO THE WORD that is in the chapter. You're basically paying whatever your university's undergraduate or credit rate is for an audiobook of that textbook.
Also, a lot of professors these days come unprepared for lecture, especially because they feel like they can just use the textbook powerpoint as a crutch if the need arises. I can't tell you how many classes I've sat in over the past year where the professor is teaching material out of order or not relevant to the current reading or homeworks.
Lastly, many professors have become incredibly boring and prone to ramble about personal anecdotes. I just had a server technology class where the professor droned on every class about some single incident in his own experience that wasn't even related to servers half the time. He also spent a good amount of time talking about the Toyota issue. Why would I want to pay attention to that?
If the university wants to ban laptops in classrooms, they should look inward and reevaluate their own faculty first. If they still want to ban technology in the classroom, extend that to the professor as well - I'd gladly pay attention to see how many of these professors and doctors can't swim without their beloved Powerpoint.