I didn't really understand the point of podcasts - it's just somebody talking into a microphone or whatever and uploading it as an mp3 - but once they introduced their availability in iTunes, I realized that it's more about the way that they're made available.
It's just like when Apple introduced GarageBand - once you make a type of technology easy and accessible, you'll get everybody from professionals to rank amateurs using it. But if you can filter through, there's some good stuff on there.
My favorite podcast is
Accident Hash. I've picked up lots of good indie music through there.