I've read that communication may be diminished as well, though, as some people don't want to make noise or cause distractions, or may be uncomfortable having personal conversations near coworkers. In short, the people most distracted by this sort of noise may be most reluctant to engage in it.

I don't have a cite here, and there's a lot of contradictory evidence anyway, but I can easily see how some kids of important inter-team communication might diminish, even if the overall amount of chatter greatly increases.

This is why I tend to agree with people that open offices are more about the appearance of productivity than actual productivity (appearance of communication rather than real communication, illusion of cost savings rather than real cost savings).