This is a fixed-episode-count podcast (they just put out the final episode) about John Coltrane and his music and his impact on jazz.
Most episodes are pretty short (~10 mins) and involve either interviews/commentary with experts on John Coltrane (or the quartet) or with people who played with him, such as McCoy Tyner, Jimmy Cobb, Charles Tolliver, Steve Kuhn.
A few episodes dive pretty deeply into the kinds of music things that Coltrane did that were so revolutionary. I found every episode to be extremely fascinating (and educational!).


David Kaffine told me about the TWiT podcast a while back and it has become a lasting staple of mine.
David Pogue is a long-time Apple/Mac and Palm fan and as a rep of the New York Times, he was one of the very few to get an iPhone before release. This podcast is a “reading” of one of his columns, but I’ve found that it is more fun to listen to as he is very enthusiastic in his reading. (FYI: he is a big advocate of speech-to-text technology and he says he does not type very much, he talks to his computer, so I guess his real talking is just more interesting than the result of translating his talking to text for reading.)
The BusinessWeek podcast is done in an “interview” style wherean editor talks to Steve Wildstrom about a recent column and asks him questions to get him talking. Again, always current and interesting.