Podcasts are something I have been using for awhile. I can't always listen to my favorite NPR shows when they come on our local station, so I have listened to Wait, Wait Don't Tell Me and This American Life among others on my computer.
I just finished listening to the podcast that Nancy Pearl (super librarian) does for a Seattle radio station. I couldn't figure out how to download that RSS feed, so I downloaded the RSS feed for the New York Times podcast.
Podcasts seem to have become ubiquitous. If you search book reviews - podcasts on Google, there are lots of choices. I can't even imagine how many hits you get if you just search podcasts.