This talk by Bill Gates was by far the most important given at TED last week (if not my favorite one).
The equation he presents is extremely powerful in the way it structures the conversation around energy and society. Simply put, something has to go to zero, but only one thing can realistically go to zero.
I also found fascinating his discussion of a nuclear power plant which burns depleted uranium as a fuel. Audacious and of a level of complexity which is hard to fathom, this "nuclear Yule log" could offer the kind of radical step-function we need to meet the needs of the equation he presents.
This is twenty minutes well-spent. My hat is off to Bill Gates for helping all us become more informed citizens, and for equipping us with a formidable tool for critical thinking. This was TED at its best.
There were a couple of other talks which also knocked my hat in the creek, so I'll post those as soon as they go up.