I think a third party that tries to get user to subscribe to your show using their own RSS feed that echoes back yours is just downright scumbaggy. I’ve actually set up an URL rewriting rule on my webserver that if I’ve got it pegged right, will prevent Creative from being able to read my feed in order to present it as their own. I actually think the Creative products in general are kind of cool, but this is rank.
There seems to be a battle for the RSS feed, and getting people to subscribe to a feed you control is the high ground. Fight the power, don’t subscribe to the Zencast.com feeds.