Podcast provides a framework and command line utility for generating RSS enclosures aka podcasts. The "podcast" command line utility recursively inspects MP3 files, extracts ID3 tags and generates an RSS enclosure for the mp3s that are found.
Podcast requires the RSS support in ruby v1.8.2, and mp3info which is also available on rubyforge. There is a rubygem for podcast available so you should be able to install with gem. Otherwise you can download the tarball or browse the code in cvs.
Comments, suggestions, patches welcome on podcast-devel