What is podcasting?
Podcasting is distributing audio or video content via RSS 2.0, or Atom. Podcast clients such as iTunes, Juice, or CastPodder(linux) allow listeners to subscribe to your RSS/Atom feed and automatically download your content to their portable audio players as it becomes available.
Podcast in Wordpress: (wordpress.com)
Create audio or video that you want to share (usually MP3 or MP4)
Upload the file to a server
Link to the file in a post in your weblog
Wordpress automatically Includes a link to the file in your RSS/Atom feed
Listeners