Thanks.to clarify from my own experience and whats been posted...
07s changed somewhere in the midyear....no white connector on later ones, but white connector on early ones. not sure if they actually made the correct cable for the non white connector later ones. ours is an early 07 and happened to have it.
no HK doesnt have the aux just because it has the HK system. i had to add it to ours.
Another note - on your HK one, does the AUX sound as loud as other sources?
Isn't it weird that the car had an AUX right there and Mercedes didn't include it?