Hi Todd,
I've never tried anything like what you're envisioning, but I know that since your podcast will most likely be a QuickTime file, then you can tap into the extended programming capabilities that QT offers. A quick Google search for QuickTime Programming found these documents from Apple's developers site. I don't have time to see if they're current, but it may provide a good jumping off point for you!
http://developer.apple.com/documentation/QuickTime/IQ_InteractiveMovies/pre...
Good luck!
Jon
TreeLine Productions
Fort Collins, CO USA
Currently producing these popular podcasts: