I realize that there are listeners out there that don't use iTunes or iPods to listen to the show. The problem is that it takes time to put together two formats, and the number of MP3 downloads was so insignificant that it didn't warrant the extra time to support it anymore. Therefore, I'm officially cancelling MP3 support and moving ahead with AAC.
AAC is an open format from Apple which offers much more than MP3 files. It supports chapter stops, web links, chapter artwork, better compression, and exports directly from GarageBand which is what I use to edit the show.
You can still convert the show to MP3 using iTunes. Select "MP3" as your import type and when you get a new episode, right click on it and convert it to MP3.