FYI - I think that the number 23 corresponding to "Sheppard" isn't Jack, but rather, Christian (his dad).
Notice how it's written in a different handwriting on the dial and the ceiling, from the other names.
The flashback in the mirror on the lighthouse showed Jack's childhood home, but Jacob hadn't touched Jack until he was an adult.
The only reason I'm not inclined to believe this is that based on pre-cash situations, Christian could only make it to the island dead, in which case MIB would be able to "take on his form" and manipulate those that knew (of) him: Jack and Claire. I can't see Jacob bringing him to the island to only be used as a wrinkle in his plan.
Hybrid Mode
