The problem with the iPod is not only Apple's claim to having a monopoly on legitimate sources of purchased downloaded music (that is, Apple's claim that Real's Harmony is illegitimate when it produces DRM music that is supposed to be compatible with iPod), but also that Apple controls who can run programs on the iPod computer.
That is, you can't simply program that computer as you wish. I understand Apple's desire to keep the DRM intact (though I disapprove of Apple's monopolistic extension of its iPod franchise into its iTunes franchise), and perhaps that could be off limits to programmers of the iPod, but the iPod's utility is inherently limited by the unavailability of third party software (not licensed by Apple) that extends it in even more unforeseen ways.
Sony could steal Apple's thunder by opening up its Walkman OS for programming in its native language, whatever that is. And the Sony version of the iShuffle, for example, could become your pocket organizer/your haiku reader/your uplifting messages system, etc.