This tutorial is based on GarageBand's informational materials. To view and download the official guides and Q&A regarding GarageBand, visit its support page here.
Specific instructions on creating podcasts with GarageBand can be found at Apple's iLife support section here. The end of that tutorial includes initial instructions on how to begin working with iTunes to broadcast your podcast.
"Take Control of Podcasting on the Mac," is a $10 e-book that is a great resource for producing and distributing podcasts using GarageBand and several other audio programs.
For extremely detailed, programmer-oriented instructions on uploading podcasts to iTunes, see Apple's Technical Specifications for podcasts.
If you are using Wordpress, the Wordpress Podcasting page is a good guide to plugins that can help you distribute your podcast.
You can find original podcasts from O'Reilly Media, one of the most authoritative sources for information on equipment and software on the net, here. In the right column, there is a "Podcasting Resources" box with links to stories you might find useful, though they tend to be a few years old.
Examples of Podcasts
Any quick browse through the iTunes Podcast Directory shows that there are easily thousands of podcasts available for subscription. Unsurpringly, many of the top podcasts at iTunes are produced by radio programs. Those podcasts produced by news organizations vary in content, quality and format. A few notable examples of podcasts that feature journalism include the following:
This American Life is a consistently popular podcast that is the same as the highly-produced radio show.
Planet Money is a daily podcast begun in September 2008 specifically to address the global financial crisis as it unfolds. It combines a relatively informal format with interviews and analysis in a show that varies between 10 and 30 minutes in length.
RadioLab is a radio program on science and ideas. But it also publishes a separate podcast that truly takes advantage of the format. Some podcast episodes include excerpts of future programs, others describe how they produce the program behind-the-scenes, and still others include audio that might not be a part of the show, but is related to it, such as the commencement speech one host recently delivered.
Playback is a monthly, semi-orgiginal podcast from National Public Radio. It's semi-original because a host, Kerry Thompson, narrates the show. But most of the material is prerecorded, archival material from decades ago. NPR engineers mix the old footage with Thompson's new commentary. Playback is a good example of what you can do using the podcast building methods in this tutorial.