I think Erik exaggerates the threat somewhat (it seems specific to ipod, not to RSS feedreaders in general), but the advice at the end is gold:
First, be sure to get a Copyright tag into your RSS feed. I now have a tag in my show’s RSS feed that reads: “Erik Marcus 2004-2005” — you can check the RSS feed for Erik’s Diner to see how and where this tag is placed.Additionally, it’s not a bad idea to end your show by saying the copyright date and providing your name. That way, both the feed itself and the content going over that feed is clearly copyrighted, and it will be easier to go after a podjacker in the courts if they republish your show under an unauthorized RSS feed.
One thing I’ll be doing shortly to further protect my show is to acquire a Creative Commons license. This will allow me to secure rights sufficient to fend off podjackers, without scaring people away from making use of my show in a fair and legitimate way. To learn more about this kind of license, visit: http://creativecommons.org/.
And finally, you should regularly check all the major podcast directories and search engines to be sure that their listings point to your official URL/RSS feed. Most podcasts, with the exception of iTunes, show your feed’s referring URL right in their show listings. To find that in iTunes, just subscribe to the show. Then go to the page in iTunes that lists all the podcasts you subscribe to, right-click on your show, and choose the “Show Description” option.
To summarize: better metadata (and specifically licensing metadata) gives you better grounds for filing a takedown notice.