In the old times people recommended that creative persons and brainworkers need silent places to work [1]. And that's totally right. Still.
But the problem increasingly is that distractions nowadays not only come from noisy work environments, but especially from software, mobile phones, twitter, Facebook, foursquare etc pp.
There are not many people that can resist checking their email almost each hour, answering SMS at once, twittering the latest news. But that's not a huge problem. People should stay informed and should be open to new technologies.
Does it make sense to ban that stuff from the workplace? Absolutely NOT. Banning something only leads to rebellion and people leaving your company.
I would rather suggest to allow and foster pair programming. People want to get things done. And if somebody is distracted all the time it is quite natural to switch to pair programming. It is fun, keeps everybody focused and is code reviewing at the same time. And - it even reduces your bus count.
[1] Peopleware, DeMarco / Lister, 1974 (Book)
[2] http://en.wikipedia.org/wiki/Pair_programming