Two presidential candidates have spoken at Google recently; the videos of their talks are now available on YouTube:
Both talks more or less took the form of interviews with CEO Eric Schmidt, plus Q&A with Google employees. I didn't see either one live; saw both on video.
My reactions to these had more to do with presentation and charisma than with substance, I'm afraid. I was a little disappointed in Clinton in that regard; she seemed a little stiff/wooden to me. And I was pleasantly surprised by McCain; he came across as smart and funny and honest and charismatic, and my impression was that he did a decent job of winning over a somewhat hostile audience. Of course, in both cases my reactions may've been colored by my expectations, which may've been too high for Clinton and too low for McCain. And (as y'all have no doubt guessed) I'm certainly more in agreement with Clinton's political views than with McCain's. Still, interesting to see them both speak.