Podcast advertising is fantastically profitable even though it&#x27;s extremely unsophisticated. As the profit margins shrink due to increased competition, more sophisticated ad formats are going to come along to keep the lights on.<p>Right now, every podcast listener hears the exact same ad regardless of where or when they are listening. It seems obvious that at some point soon, podcasts will include a custom code for &quot;insert ad here&quot; and an ad exchange will bid on that 30 second spot and put a targeted ad there. Currently, the MP3 + RSS format of podcasts doesn&#x27;t support this degree of sophistication which is what Marco is alluding to with it&#x27;s walled gardens comment. There&#x27;s a goldmine for whoever can figure out how to move podcasts into a vertically integrated format and define the platform.