Surprisingly few academics in my field are on Twitter. I'm one of them, and did my share of tweeting through ICC. Other than me, only four other people used the #icc2010 hashtag: @jabriffa, @csgrad, @gvrooyen, and @mayanm. This is at a conference with around a thousand attendees! Why the low uptake? It's not as though Twitter is brand new.
At ICC, it struck me that Twitter would be a great tool for participants to get the most out of large conferences. With 20 parallel sessions and over 1000 accepted papers, ICC is enormous -- it would be physically impossible to see more than a small fraction of the available presentations. To deal with this overload of information, Twitter would be an ideal tool to quickly find out about interesting sessions. For example, say you're at a huge conference: tweeting audience members could be giving real-time information on which sessions are worth attending, which presentations are the most engaging, and which papers might interest you. You might change your plans to swing by and check out a session that seems interesting -- or if you didn't have time, you could make a note and check out the papers in the proceedings. Otherwise, seeing these tweets would be a nice way to find out about researchers with interests similar to yours -- and for them to find out about you.
This networking effect of Twitter is a key feature that goes beyond conferences, especially for junior faculty and graduate students. Research -- even excellent research -- doesn't usually attract attention to itself; especially in a huge field like communications, it's incredibly hard for individual researchers to boost their signal above the background. As a result, researchers need to be advertising their work all the time, using every tool they can find. Twitter is ideal for this -- for instance, whenever I publish a paper or give a talk, I mention it on my Twitter feed, and it is broadcast to all my followers. (Of course, the trick is then to get lots of followers.) This principle applies to all social media, not just Twitter: I maintain a personal website, this blog and a YouTube page as well as Twitter, to make it as easy as possible for people to find out about my work.
As one commenter on Mitzenmacher's blog put it, any graduate student wanting an academic career should have a blog. I'd go further: graduate students and junior faculty should be blogging, tweeting, and doing whatever else they can to get their name and work out there.