A podcast is another way to engage Your Fans — and prospective fans—in a medium similar to your audiobooks. The more people you get to listen to you, the more people will want to continue listening to you. And that’s what drives sales. So go ahead, get started.
Don't worry about the technology. If you’re an audiobook narrator or Producer, you probably already know that creating audio can be as simple or as elaborate as you'd like. If you’re not, just know that podcasting can be as easy as plugging in a cheap USB mic to your computer and pressing record. Or, if your prefer, you can use always more sophisticated tools like studio mics and mixers.
How to Create a Podcast (A Step-by-step Tutorial from About.com)
http://radio.about.com/od/podcastin1/a/aa030805a.htm
So what should you talk about? Talk about anything you want! It’s probably a good idea for your podcast to be related to your work or interests as reflected elsewhere (like on your blog). But be creative. For example:
Take a tour through the iTunes Podcast directory for some sample podcasts and see what inspires you.