EdTechTalk is a great place to find other educational podcasts, and since they are "webcasts" if your schedule permits you can tune in "live" and participate in these shows in the live chat / backchannel they use on EdTechTalk.
I definitely have had some of my best "professional development moments" from the past year thanks to Seedlings in particular.
It's not strictly considered educational, but my favorite podcast is The Splendid Table (found it on iTunes). Great cooking show, but more than recipes and reviews. They spend a lot of time using the sounds of locations to bring you in to the scene. Sounds from marketplaces, kitchens, etc. Well-chosen music interludes. Care taken to make the sound quality the best they can, even when the interview takes place over a phone connection, etc.
Maybe not truly a podcast, but can be saved as a podcast: Ted Talks. I find each of them utterly fascinating. These creative and knowledgeable people keep my curiousity and wonder alive. I also use them with my gifted students for cutting edge topics, and as role models of people making a difference out in the real world.
We have been offering some training in Texas to our science/math education community with the hope that our folks that are attending face to face professional development would capture some of the content for sharing across the state. We provides some basic training with Garageband, iMovie, and audacity. You can watch the results as they are posted on our Podcast Index page. These are all beginners, so the quality varies. Most of these authors are using Poderator.com to generate the feed. Your feedback is welcome.
Texas Regional Collaboratives for Excellence in Science and Mathematics Teaching
For secondary social studies teachers and students, I highly recommend Dan Carlin's Hardcore History easily found at Podcast Alley or through Itunes. His programming, research and reading lists are incredible and are wonderfully produced. The way he covers historical topics and ties them in to current events really spark an interest for the subject.