:k:
FrankenPaula wondered a while back if anyone had been following this mystery, which appears to be tied in to BMW Films somehow. One possible starting point, as pointed out by Trallyus, is at the Apple site where you can go to www.apple.com/mpeg4, scroll to the bottom of the page and click the linked :k: to begin your quest. A BMW Films fan has a site called the Deciphernaut HQ where you can find some hints, and the MacRumors forum has also been discussing the mystery.
Update: The rabbit hole is here – http://209.46.98.251/.
Updated again: The true rabbit hole is here – http://www.cbmlt.com/ – thanks, Tien_Le!