Download photos via usb from 1D4/X to iPhone?

You could use an Eye-Fi card in SD -> CF adaptor. There are several available on Amazon. I don't have first hand experience with it but one of my colleagues does. It's not 100% but it works in a crunch. Some might work better than others.

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A few of my photos:
http://www.jackkurtzphotography.com or
http://www.sportsshooter.com/members.html?id=4177 or
my PhotoShelter Archive
http://kurtzjack.photoshelter.com/