This post is the first time I've seen these thoughts pulled together, summarized as:.
As a presenter, the idea of presenting while people are talking about you is
disconcerting. But to balance that, there are huge benefits to the individual
members of the audience and to the overall output of a conference or meeting.
Dealing with the "back-channel" is a fascinating challenge for presenters at conferences. Perhaps now this happens more in IT conferences than other industries, but if that's true, it will change quickly.
I'm sure professors are already dealing with this too.