I too love podcasts but I don't think the educational ones necessarily teach me much. Listening is too passive, especially if you're doing other things. If I'm not following a book or paying close attention, I'll put the book down. But its easy with well produced podcasts and audio to just continue listening while zoning out. I've listened to hours on a subject but if you were to quiz me on that subject I would be clueless. I don't think the same would be true if I had spent hours reading a book on a topic.