I thought this was going to get me somewhere.
When I deleted a podcast, I got this alert:
Do you want to move the selected podcasts to the Trash, or keep them in the iTunes Music folder?
Only files in the iTunes Music folder will be moved to the Trash
[Cancel] [Keep files] [Move to Trash]
So, I thought it was going to lose it's podcastiness and become a plain-old-vanilla mp3 file, but when I double-clicked on it in the Finder to open it with iTunes, it plopped itself right back into the list with the other Escape Pod podcasts, except it got stripped of the show description.
The versions I download manually from the web site via the browser get dumped into the iTunes general Music library, and they do not behave like podcasts.
PS. If one limits (ie. rations) one's consumption of podcasts, is that called "podcastration"?