I can tell you from personal experience that the folks who have a laptop present during a business meeting do indeed get distracted.

Imagine having a business meeting about the development of a website. Six people are present, four of which have laptops open. The only two who didn't were myself and my co-worker. We've been holding these meeting about once a week for a solid month. The result? My co-worker and I seem to have a whole lot more documentation and are more organized that most of the others involved in the project. The reason? I think the others are just getting way too distracted with what their doing with their laptops and not enough on what is being said in the meetings. You can take good notes with nothing more than a pad and pen and will retain much more information without the distraction of a laptop.

My wife is a law school student who is fixing to graduate. This year (and part of last year) she choose not to take her laptop to class with her. Instead she opted to take only a notebook for taking notes and such. The result? She found that she was less distracted, payed much more attention to what was going on in class, and retained a whole lot more knowledge.

There's also something to be said about smart phones as well (ie. iPhones, Treos, Crackberrys, etc). I can't tell you how many times I have been interrupted during a meeting and/or presentation because someone absolutely had to either answer their phone or check their e-mail. It's like Pavlov's dogs with some people. Some people just don't understand that there is a time and a place to mess with your phone. During a meeting and/or presentation isn't it. You should concentrate your attention on the business at hand and save the phone call and/or e-mail for processing at a later time.