This is a great idea, beautifully implemented:
I like the fact that they’ve broken down the podcasts into newbie, beginner, intermediate, and advanced. I especially like their business model: Distribute the podcasts for free, and charge for the additional learning materials.
They have chosen the blog format to present the material, and have made it available for subscriptions via iTunes and comments are open. Not to mention, a fairly attractive site design. Well done, useful, and innovative.