Boston -- I just saw a new company that lets you listen to podcasts on your phone: Foneshow. It's a two-person company, but I'm impressed by how well the small team has thought through the mechanics of taking audio shows and porting them to a phone.
It works like this: you subscribe to a podcast either from the Foneshow site or from the podcast's home page (if the publisher has put a Foneshow sign-up on the page). Then, whenever there's a new episode of your podcast, the system sends you an SMS message with a unique phone number. Most phones will let you easily select the number and dial it. Foneshow uses that number in combination with your caller ID to then play your podcast over the phone.
Once you're listening the podcast, you can use voice mail-like keys to pause or rewind the playback, unsubscribe from the show, or forward it to someone else. Coming soon: the capability to speed up the podcast (without raising the pitch), which will be great for interesting but slow-speaking 'casters. Maybe to come after that: advertising, as in, "Press No. 5 to be connected to Ronco!"
I did a "Real Deal" podcast with Tom Merritt that I found on the site here. The Foneshow crew needs to put some work into its site design and usability, but the core functionality looks good. One problem: since Foneshow streams podcasts over the air, I can't use it to listen to podcasts on my cellular-free subway ride to work.