Ads can (and already are) stitched into podcasts based on download location. GeoIP isn't perfect, but it's enough to do location aware advertising in the same vein as terrestrial radio..
Oh wow, I hadn't considered that but it's obviously simple to do. Here's a funny thought: your script downloads the file with requests from two IPs associated with different locations and gets a union of the audio for you to listen to (thus cutting out any location-based segments).