Craig Syverson at Gruntmedia has created an excellent explanation of how subscribing to podcasts works. Have a look at the video and the basic overview page. I wish I could get my videos to look that good, so I might use this video when explaining what podcasting is to academic staff here at Edge Hill University.
And while we're on the subject of Podcasting, the Learning Technology Development manager here at Edge Hill is running a couple of sessions about the use of audio technologies in academic courses. They'll be called "iPod Therefore iLearn" and "iPod therefore iDo". You'll need to book soon as they are running over the next few weeks, and they are open to everyone, even those who aren't staff at Edge Hill.