Quite a few conferences are using Twitter walls these days, i.e. a screen that shows tweets related to the event in real time. They help attendees see what's going on, in the talks but also around the event as such.
Twitter walls that are visible to the audience during a talk are a real challenge for the speaker, though. It means that any comments that are being tweeted are immediately visible to all the other attendees. So that remark which - in the times before Twitter - you would quietly make to the person next to you suddenly gets a much broader audience. This applies to praise as well as to criticism. Even more so to criticism, actually.
