The app also allows you to purchase songs you hear at the iTunes store, and has a favorite channels setting. The app runs on OS 2.2.1 but has been tested on the just released iPhone/touch 3.0.
The channel selection is set up for both Sirius and XM subscribers. Sirius is offering a 7 day free trial for non-subscribers to try the service and see if they like it. This app has been expected for a long time, ever since the iPhone was first announced. A lot has changed in satellite radio since then, and it will be interesting to watch the dynamics of people getting their satellite radio with an Apple product rather than a dedicated satellite receiver.
Happy listening. (Update: Readers are telling us no Howard Stern, no MLB or NFL games. Oh my.)
Thanks to reader John Mackay for the tip.