I'm pretty confident that danah boyd's was the most talked about talk during the Personal Democracy Forum 2009 Conference in New York City. I can say this because she was mentioned more than 750 times in the twitter stream during the 2 days of the conference. Michael Wesch got a lot of buzz - almost 600 mentions - and Jeff Jarvis and Mark Pesce (who gave a really powerful talk last year too) did well, each getting almost 500 mentions. But boyd topped them all.

And the day before it was "energy." At least it was in the Congressional Record according to the Sunlight Foundation's Capitol Words project.