I thought I'd come back and report on what I've found and listen to regularly (all are available in iTunes).
Aero-News Network: great all-around aviation news, daily. Covers the gamut, but with a GA perspective (especially in the Special Features - daily 20 minute interviews with various industry folks).
http://www.aero-news.net
The Finer Points: weekly, 5-10 minutes, wonderful training/safety focus and good music
http://www.thefinerpoints.net
EAA AvCast: every two weeks, around 10 minutes, AirVenture focus.
http://www.eaa.org/podcast
PilotCast: around an hour, haven't seen an episode in a few months, but I'm going through old episodes, good GA "hangar flying"
http://pilotcast.libsyn.com
Uncontrolled Airspace: similar to PilotCast, every week, about an hour, with current episodes
http://www.uncontrolledairspace.com/
UND Aerocast: great training videos, monthly, usually 5-10 minutes
http://www.undaerocast.com/
Please let me know if there's anything else out there, specifically experimental and/or RV-related.
- Jeff