In case you’re a bit late to the party, a podcast is basically the Internet age’s version of Talk Radio. They even do radio one better: listeners typically subscribe to podcasts, and can listen to “episodes” on-demand.
So why should wordpreneurs care? For marketing and publicity. To reach the podcast listener market, get yourself mentioned, interviewed, whatever, on a podcast.
There’s a bunch of them, covering a wide variety of special interests. So whatever it is you’re trying to sell, you’ll likely find one or more podcasts where you can pitch yourself. And to find them, just go to the PodSearch site.