I saw your similar comment on my blog and responded thus:
Teachers who have had problems with children passing notes would never have suggested banning pen and paper.
It's also possible that paper and computers have distinct properties (they're local, not networked) that make them unlike laptops and thus inappropriate for direct comparison. I don't think your analogy fits.
So let them be distracted. That is their choice. Unless they are disrupting others, you should stop babying your students and let them use or misuse the tools as they see fit.
Students don't exist in a vacuum: they can also distract others and lower the overall quality of discussion and the classroom experience. In addition, it can sometimes be helpful for mild forms of paternalism to be used to nudge someone in the right direction. If students don't like the very minor restrictions in my class, they're welcome to take someone else's. Few do.
I don't think it morally wrong, or something like that, for students to have laptops in class, but apparently I'm not alone in noticing the drawbacks they can have.
If you can't get their attention in the first place there are only a handful of possibilities: 1) The subject stinks. 2) The material stinks. 3) The students stink. 4) The teacher stinks.
It's also possible that humans have a tendency toward distraction that Internet access in particular enables, per the Google article, or that people often aren't very good at regulating themselves, per Paul Graham's essay; I'm often not good at regulating myself. Hence it can be desirable to remove the means of distraction as a way of removing the distraction itself.
Banning an item that might help a student who is there and wants to learn so that a lazy student that doesn't care is not distracted is completely irresponsible.
I beg to differ: banning an item that might has a net negative effect on the classroom is responsible because it appears to improve learning and the classroom experience, per the above.