Hi Shawn,
I tried your linaro-media-create changes ... I put them in this branch: https://code.launchpad.net/~dave-martin-arm/linaro-image-tools/mx51evk-fixes
There are still a couple of errors which stop correct installation of u-boot when using linaro-media-create --image_file.
I still couldn't get a bootable system though. The U-Boot environment didn't get set up correctly.
Do you have any thoughts? More details and a run log from linaro-media-create are here: https://bugs.launchpad.net/u-boot-linaro/+bug/656962
Cheers ---Dave