Nassim Nicholas Taleb's talk was about how prediction is so inaccurate, and that we do a very poor job in thinking about the future in two main areas: first, we overestimate how confident we should be about our predictions, and second, we tend to underestimate the effects of the unknowable and rare. It was a fascinating look at the limits of what we can say about our own future.
The second talk was the one that followed Taleb's at PopTech, a lecture by Robert Trivers about the role of deception in nature and psychology. He starts with simple arguments about how evolution fosters species to deceive each other, then how deception plays a role in communities of a single species, and finally how humanity has integrated it into our communities and cultures. Combined with this is a strong argument about the role deception played in the US's dealings with Iraq, leading up to the current war and occupation. This talk was chilling, but not entirely hopeless.
Both are recommended listening.