Old folks tend to repeat themselves, so bear with me if this is redundant. A cursory search of Science Blogs turned up a comment in response to Razib’s post in Gene Expression that calls attention to the video of Sean B. Carroll’s 2005 HHMI Holiday Lecture on Charles Darwin and the development of the theory of evolution. Carroll is an excellent speaker. He aims the topic toward high school students in this accessible and enjoyable seminar. The video (below the fold) is ~ 1 hour in duration, but well worth the time.
ETA: Thanks to commenter Chris for pointing out that DVDs for a number of the HHMI lectures are available here. I just subscribed to the podcasts myself.