Casting the Net is rich in podcasting resources for teachers

Casting the Net is an EdNA project that aims to help Australian educators "explore ways that the creation of audio materials can empower learners, especially those with low levels of literacy and with auditory learning styles."

Here's the initiative's Moodle page, its blog, its podcast, and a wiki for a presentation by Sean Fitzgerald on MP3 Players, Podcasting and Online Audio Materials in Education. A zillion great links for teachers in the wiki, seems like a really good starting point.