The Pomerantz Report has a post Stephen Hawking Lecture - NASA's 50th Anniversary. I haven't listened to the lecture itself yet, but Will gives the impression that it's a good one.
Update (April 25): Will has another post on an article he wrote for ASK NASA, and a recent talk based on the article, about lessons NASA can learn from teams like those in the Lunar Lander Challenge. You can get to his earlier post on the ASK Magazine article, and also the article itself, here.