I’ve been following the discussion here with interest. Personally, I don’t Tweet during presentations (notes in 140 characters requires too much concentration for me!), but I do like being able to follow along using the hashtags. Other people have put the case far more eloquently than I could, so my only contribution to this is as a reader rather than a Tweeter.
From my point of view, I would really appreciate it if there was a way to separate out the Tweets from people *at* the conference from people Tweeting *about* the conference, since separating the notes from the general chatter can be incredibly difficult. Maybe Twitter lists could be used for attendees, or perhaps they could use different hashtags? It’s a classic information overload issue, and I refuse to believe that librarians can’t find a way to solve it!