Radiolab has been getting some love from quite a few of the sites I read (Snarkmarket originally turned me on to the show), so I thought I'd offer mine as well. I don't listen to the radio or to podcasts, but lately I've made an exception for Radiolab. It's about science, the editing is wonderful and unique, Jad Abumrad is one of the best radio voices I've ever heard, and to top it off, their shows are really fascinating.
Their show on Memory and Forgetting from last June is particularly good. If you don't have time for the whole thing, the Adding Memory (especially Joe Andoe's story) and Clive segments are almost must-listens.
You can listen to Radiolab on their site, on a variety of US radio stations, as a podcast, or though iTunes.
Update: Radiolab did a session at the Apple Store in Soho about their editing process and thought process. (thx, dan)