I've listened to podcasts from NPR and The Onion for a few years now. I've listened to some educational podcasts and Voice Threads and have a VT account. I like being able to use iTunes to subscribe to updated podcasts.
The best podcast I found in my recent searching is Joyce Valenza's 21st Century Librarian's Manifesto. It's got an accompanying wiki for people to edit and add their thoughts and vision.
I would really like to encourage my students to do some podcast-based booktalks or book reviews. At this point, I don't really have a teacher who will work with me but I'm working on that for the coming school year. I know that if we get them started it will open a whole new aspect to my library program and engaging learners in the use of various web2.0 tools. I'm hoping to learn more about podcasting at PSLA's annual conference in May.