Recommended podcasts
An extremely professional audio podcast on Cocoa done by Steve Scott (Scotty). Scotty interviews many of the best Cocoa programmers out there, each spending time on one framework or concept. He has a natural talent for interviews and does a great job in his production of the episodes. He has since expanded upon this show to form the Mac Developer Network, which I highly recommend you become a member of.
Another podcast by Scotty, where he pulls together groups of Cocoa developers and gets them to argue over things like whether exceptions or NSError are the way to go for error detection in your code.
Yet another podcast by Scotty, this time one where he gets prominent Cocoa developers to give their life story. A large part of what makes Cocoa development so much fun is the community. Each one of these developers are friendly, helpful people and it's great to hear the unique stories of how they came to be where they are.
A new podcast organized by Scotty, this one brings together all of the previous individual podcasts like Late Night Cocoa as sections within one show. New sections on accessibility and interface design round out a great amount of Cocoa-related content.
A relatively new podcast that delves into both the development and business sides of iPhone applications. They've had some interesting guests on the show so far, so it's worth a listen.