Looks like podcasting is taking off quite a bit. iPodderX a Podcast client for
the Mac is currently listing 1635 podcast sources. Engadget provides the most
popular podcast out there right now.
The iPodderX client for Mac uses RSS 2.0 to retrieve new podcasts. The software moves audio files into iTunes where they then can easily synched onto an Apple iPod. Engadget published a How-To on podcasting a while ago. More details on the iPodderX site.
iPod deals on Amazon.com.