Firefox Extension for Podcasts?

OK... I use Firefox. You do too, right? Anyway, I was over at the Grassroots Music site and they now provide PodCasts of new music... What is a podcast? OK - imagine that you like a specific radio show "Prarie Home Companion" or something... Now, imagine that it was converted into an MP3 that could be downloaded from the web onto your PC or portable MP3 player (or Ipod). Now imagine that instead of manually checking & downloading - you can simply subscribe to the feed. It is like broadcasting, only for Ipods (not really, it's just that they are the most trendy) so it's called PodCasting.

So, here's where I am - I want to subscribe for some PodCasts, but I don't know what programs are best - What I'd really like is an extension for Firefox that will do this for me. Has anyone seen a Firefox Extension for PodCast subscription? Please let me know...