speaking to an audience; understanding online backchatter

While the linked article is geared more toward conferences or seminars, it is very applicable to teaching - especially in higher-ed. One of the issues not addressed by the article below is that the backchatter is not all via Twitter. At the very least, there is Facebook and IM chatter going on as well. Do any of you have any stories or advice for recognizing or taking advantage online chatter during class time?

How to Present While People are Twittering | Pistachio:

"So the next time you present at a conference, instead of being confronted by a sea of faces looking at you, you may be phased by a sea of heads looking down at their laptops. The challenge is how to adapt to presenting with the back-channel."