Something interesting:
The latest version of iTunes has just come out, and it has a new option for Podcasts. You can subscribe to certain Podcasts, and even publish your own with it.
Requirements are an RSS feed of the Podcast, info on the Podcast itself(Including artwork for the Album Art feature), and some extra info not in the feed. It's free to publish one, and the only requirements are that they're in AAC or MP3 format and don't have any copyrighted material or bad language. They can be reviewed before they're published too, and won't be added immediately.
When you subscribe, you'll be notified of updates and can download the file directly through iTunes(adding it to your Library for synching with your iPod too)
More info can be found through iTunes itself, they have a nifty FAQ.
EDIT: I've just been checking the system, quite userfriendly and subscribing just involves clicking a few links. It's all free too, and quite a few Podcasts are already available. Subscribed Podcasts are automatically updated if a newer version is available during your(pre-set) check time.
With the latest iPod software update you also get a new Podcasts entry, which lets you listen to your selection.