How does it work?

Just curious how music distribution works in this new-fangled digital age. I'm sure all the music stations these days pay their dues to ASCAP and the like, but I doubt every music station has a bank of hard drives delivering MP3 tracks to the transmitter. Seems more likely that it's all delivered via the 'net these days in real-time. I'd guess they all have some good playlist software that works it all out and probably have something that's a cut above Rhapsody or iTunes.

Anyone know?