Podcast is a simple library and command line utility for creating podcast files from a directory of mp3 files.
Podcast will examine mp3s, extract metadata from ID3 tags, and build an RSS file which can then be used by podcast clients to download the mp3s.
To install ruby-podcast
gem install ruby-podcast
Once you've installed it you should have a command line utility you can run on a directory of mp3 files:
% podcast --dir my/mp3/dir --out podcast.rss --title "Title" --description "Description" --link http://mypodcastserver/
This used to be hosted at http://podcast.rubyforge.org/ However, that version no longer works with newer versions of Ruby.