Indie Travel Podcast: Created by a New Zealand couple with a mad passion for travel, this podcast series is usually updated once a week. It's a great source of audio information on topics like couchsurfing and language study. There are also video podcasts and text articles, with an extensive archive. You can subscribe on iTunes, too.
Lonely Planet produces a huge range of podcasts covering most of, well, the planet. They're also available on iTunes.
Canadian travel journalist Bob Fisher offers streamed informal interviews on travel-related topics--everything from sports tourism to the relationship between travel and climate change--on his Travelosophy.ca site.
And finally, there's a good list of travel podcasts in this PCmag.com article from June 2008.
