Just purchased Nicecast from Rogue Amoeba. It lets you broadcast by pulling in either the audio output from an application or the line-in. I’m using it for making a local stream to play on the Airport Express-connected speakers via iTunes. BBC’s back in the air. Once I get back a router I control myself, I’ll try and play with the public broadcast bit. It’s really easy to set up and the 40-dollar price tag is ok, though it’s not a bargain.