FlyTunes, which I first found out about during CES, is supposed to be debuting today. The service allows you to listen to internet radio with your iPhone or iPod Touch.
FlyTunes is just a web application that can be accessed through mobile Safari, but has some great features, you can customize stations on your PC or Mac and then login and listen to them on your iPhone.
One more interesting tid bit is that it can queue up to a half hour of music to listen to if you happen to be leaving an EDGE or Wifi covered area, and all of this is free.