I answered this question extremely crappily at Blogs With Balls this past Saturday so I wanted to clarify some thoughts here.
If you’re looking to make worthwhile money directly from a podcast, forget it. At this point, producers who have monetized their shows are the exception, not the rule. Bill Simmons has his “Subway Fresh Take Hotline” and Adam Carolla does his sponsored reads but beyond that are a whole lot of talented people that have created programs to boost awareness of their brand / other talents.
Whether it’s writing, TV hosting, or painting, a podcast can act as a wonderful promotional tool for those skills. Jonah Keri is a recent example of someone who podcasted for free (or rather, a small loss) that has been hired fulltime at Grantland to write and continue his podcast. Keri performed the tedious task of hosting 56 unpaid episodes and is now doing it on paid time under the ESPN umbrella, but writing remains his bread and butter. I’m sure he’d tell you that the show, in part, helped get “The entire Jonah Keri package” the Grantland gig.
A concrete podcasting business model does not exist as of today.