Correct me if I am mistaken, but AFAIK, the current options that connect the built-in audio nav of the Prius to the iPod (or any other portable music player, for that matter) do not allow directory navigation. I don't find a flat compilation of 1000's of sounds listed as song1, song2, etc, too helpful.

So with our BC Prius that has the external 6 CD changer, I think I will end up changing out the CD player to one that reads MP3 or Ogg.

This way, I'll have about 3.5 GB of compressed music split into 6 categories without cables, and no iPod connect/disconnects.