Bloggers learned this early on as well. While a blogger can certainly edit an entry, there are lots of enterprising people out there that can and will take screen shots of interesting content. Google cache is also not your friend in this matter.
Podcasting falls under the same rules. Defintely, positively never say anything that you don't want the whole world to hear in a podcast. It's never happened to me, but I can only imagine how painful it would be for something stupid that I've said to be played back to me. It's one thing to have an email that you wrote presented to the world, but your actual voice,,,? Eww,,,
Companies not only have to worry about the possible legal ramifications of what is said in a corporate podcast, but they also have to worry about just generally looking unknowledgeable or boorish. That's likely the reason why so many corporations run their podcasts through legal and marketing before they go out. Which, coincidentally, is also the reason why most corporate podcasts are about as exciting as watching paint dry.
Nobody said podcasting was going to be easy so take it easy on what you say. But do it genuinely and not through a legal-sanitization.