The National Academies (of science, engineering, and medicine) have a weekly podcast called "The Sounds of Science" (you can also subscribe to these podcasts through iTunes). There's a wide range of topics, and the podcasts (each typically 10-11 minutes) are most often tied to social and educational issues. I listened to a recent one, "The Reality of Virtual Reality," and another one on "Grand Challenges for Engineering," and both were very interesting and well done.
Related to the second topic is their Grand Challenges for Engineering web site. The 14 challenges they have identified include making solar energy economical, preventing nuclear terror, and reverse engineering the brain. And those are just the easy ones (not really).
The National Academies also have a lot of great publications, some of which are available as free PDF downloads simply by registering for their site. Good stuff.