I was recently directed to a great guide to ensuring that your podcast is legal. The Podcasting Legal Guide is hosted on the Creative Commons wiki and provides an overview of legal information every good little podcaster should know and understand. The Guide was created by the following parties:
The Berkman Center Clinical Program in Cyberlaw http://cyber.harvard.edu/
Also, remember that we have a Podcasting Fundamentals Tutorial available that will teach you the basics of creating and publishing your very own podcast.