I was just about to post a similar comment, after using an ohm meter on several cables to see how they were wired. Once realizing that a standard A/V and standard audio were not compatible, it dawned on me that the only thing Apple did is make their latest IPOD backward compatible for audio output. (except for the weird left/right swap)
Most audio jacks have only one ring in the position where IPOD's have a 3rd and 4th position. This implies that there must be a protection circuit, since the audio plug would short video to ground.
Thanks for the graphic! Handy to pass on to other IPOD owners.