Actually there sort of is. If you could mount the iPhone/iPod as a USB device (this would require a complete reformat of the iPod, so I'm not sure it's worth the trouble), it would most likely work in something like WiiMC.
Pretty sure some Linux distro could access music from iPods in a media player that came preinstalled with it. Can't remember it's name though. Probably xWhiite or Bliight.
