I attended a seminar at Educause 2008 today: "Millennials and Web 2.0: 'Prosumer' Education in Practice" long title but great presenters, AJ Kelton and Sarah Robbins-Bell (intellagirl)
I've been to a few web 2.0 presentations over the last few years and intella-g knows her stuff. I've borrowed a few of her ideas and recommendations for web2 at my Uni.
Hey, she actually gave me a good reason for this anti-social, (actually I profess as my religion to be a 'radical individualist') to use Twitter...
If that's not a good speaker, then I haven't heard one.