Actually a whole bunch of them are, at www.groktalk.net, but mine in particular is at
http://www.groktalk.net/blog/KateGregoryPresentingWhyCIsntCEnough.aspx
My favourite part happens after the camera is off and we go to credits. ![:-)](smilies/happy.gif)
You can stream these, download them to watch at your leisure, or bring them down in the background with BITS using a tool like DrizzleCast. Full instructions are at the main URL. We've set each talk up as a blog entry so that you can comment and ask questions: you'll lower my workload if you comment there rather than here.
Kate