Sirius/XM is not quite a stranger to the iPhone - uSirius was released back in June
of 08 to jailbroken users, and worked... and was buggy at best. The app was released by Millard Software, whose namesake Jason Millard is now teamed up with the folks at StarPlayr
to release a prettied up, completely revamped, AppStore Sirius/XM app under the StarPlayr name. It should hit sometime this month.