So, I ran home and got my portable 2.5" hard drive, which has a USB - Laptop IDE bridge on it. It works, right up to the point where the light turns red. Looks like his hard drive is completely toast.
So, we ended up having to build a replacement from scratch on a spare, with just the minimum he needs to be able to do any work at all, and we have to have it finished before the end of business today so that one of the other guys who are meeting him in Vegas can take it to him. I volunteered to run it on out to him, but they wouldn't pay for the tickets :(
Moral of the story? Don't forget to back up your stuff to a different PHYSICAL drive (backing up to a different partition is kind of useless if the drive fails), because drives do fail, sometimes with absolutely no warning whatsoever.