Looks like Apple may be expanding from a straight POS system for music into streaming - they are talking to LaLa:

The Lala service lets users listen to any song on its site once for free. Customers can then opt to buy the track for 10 cents and listen to it on the Web. The service differs from iTunes because the music is stored on servers via so-called cloud computing, instead of being downloaded to the user's computer. If customers decide to download a track, the cost is 79 cents -- compared with iTunes' price of 69 cents to $1.29.

Not quite as easily "fire and forget" as Pandora, but it sounds like an interesting expansion out from iTunes.