There is one thing missing from this thread that people haven't taken into account. Jack was super upset at the death. What would have happened between being on the island and getting off that would suddenly make Jack so upset about Jacob? Another thing people keep pointing out which I think may have relavence is that the coffin seemed rather small. But I can't think of a dude from the show who is small aside from maybe Ben and Walt but we now know that Ben is still alive and I don't think its Walt. So now I am confused...

I think Jacob might prove to be a child, not unlike Walt. Fits my long-standing theory that the younger you are the better you can control the power of the Island (or draw upon it).
That's why Jack would have eventually found compassion for him?

Or as usual I'm way off base.

__________________
"The Naked Gun!"

Frank Drebin remembers a lost love.

Frank: It's the same old story. Boy finds girl, boy loses girl, girl finds boy, boy forgets girl, boy remembers girl, girls dies in a tragic blimp accident over the Orange Bowl on New Year's Day.

Jane: Goodyear?

Frank: No, the worst.