A podcast is just a blog with RSS/Atom feeds containing media enclosures. Once you've made a blog, ikiwiki gives you two ways to turn it into a podcast.

Basic podcasting

Put a media file where you'd put a blog post, and your [[!inline ]] directive will include it as a media-only post.

Fancier podcasting

Put the media file where [[!inline ]] won't directly include it. Write a blog post with [[!meta enclosure="WikiLink/to/media.mp3"]] and your show notes.

See also migrating podcast to ikiwiki.