Backchannel
Description
"More and more, services like Twitter are being used as "backchannel" communications mechanisms by which the audience can provide non-interruptive feedback to each other, and to the people running the event." (http://www.marrowbones.com/commons/technosocial/2008/03/anatomy_of_a_mob_the_lacyzucke.html)
More Information
How the Twitter backchannel turned the Zuckerberg SWSX audience into a mob, at http://www.marrowbones.com/commons/technosocial/2008/03/anatomy_of_a_mob_the_lacyzucke.html