Steve Lacey: When I was first thinking about this, my mind was in the RSS space, but I had a niggling feeling OPML might be the better choice. Then, after Dave's post I realised that the reason to use OPML (other than there are editors about) is that it's hierarchical.
http://www.steve-lacey.com/blogarchives/2005/06/podcast_shownot_1.shtml
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