Sorry, I'm slacking lol.
Yes, I do get cover art with my white cable and iPhone 4S. On the occasion that my battery gets low before I go to bed, I just swap the iPhones rather than pulling out my car charger that is buried deep in the bowels of my console. I get the exact same functions with my 4S - aside from the 4S being activated so I get Facebook, Wiki, Pandora, etc.
I'm not sure what the issue was. Maybe it was software or some minor option/regional variation. Idk. There are all kinds of regional program differences that are activated/deactivated depending on the market, like mirror fold with locking or holding the lock button on the key fob, rear fog lights deactivated in the U.S., etc.