"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)
Example of Backchannel effects
How the Twitter backchannel turned the Zuckerberg SWSX audience into a mob:
"Twitter provides a communication channel which augments, rather than interrupts, existing communications. As such, it makes it possible for people to communicate both within a group, and (in structured events) to the leaders of a group, all without disrupting the normal progress of the activity. If that sounds like too much for a panel discussion or interviewer to manage, consider that most reporters in traditional media (not to mention football quarterbacks) have similar mechanisms for receiving information while they work. Whether increased multitasking is a good thing from a quality standpoint is a different issue. For that, look at the research that Howard Rheingold has been doing in the areas of multitasking and backchannels.
The Twitter backchannel can definitely have a positive influence. As a remote observer of SXSW I was not only able to receive ongoing summaries of sessions, but I could suggest questions for attendees to ask, and provide resources to panelists while they were in an active session. The backchannel can provide a low-key mechanism for alerting presenters to issues, offering support, and of course organizing and coordinating group actions. The issue, is how to keep group actions from growing out of control. I believe that requires education (or perhaps just a new generation of users) about the differences between virtual and real communication, and the dangers of transporting emotions directly from one to the other. I believe it also requires responsibility on the part of backchannel spectators.
There is a tendency in online discussions to let flames burn themselves out. After all, it's the virtual world, not the real one. "Getting involved" can be a pain. But as the SXSW events show, the boundaries between real and virtual get thinner every year, and virtual emotions can cause real-world harm. I greatly admire Sarah Lacy's ability to deal with the abuse she has gotten and move on. A reporter has to have a tough skin, but it still can't have been easy. She didn't deserve the abuse that was dished out on Twitter, let alone what happened in the auditorium.
As citizens of the online world, we have a responsibility to step forward when we see people misbehaving. It doesn't take much to tone things down. People need to be reminded that the target of their frustrations is a real person. They also need to be reminded that their persona, though virtual, has its own reputation to think about. The members of an online mob are in fact far less anonymous than those in a real mob. I was rather shocked when I happened to notice that one of the tweets I quoted above was actually made by someone I follow on Twitter. It was more sophomoric than mean, but it still contributed to the overall mood. Finding out who said what during the conference is a simple task for anyone with access to Google. We need to live our online lives under the assumption that everything we say, and everything we do, no matter how private it seems, is going to contribute to our overall reputation. That's a good thing, but it takes getting used to." (http://www.marrowbones.com/commons/technosocial/2008/03/anatomy_of_a_mob_the_lacyzucke.html)