I'm not sure if this has been commented on elsewhere (if it has, I didn't find it). Anyway, I'm re-watching the whole series, and in the season 2 episode "Two for the Road," when Sawyer is reading the "Bad Twin" manuscript, Jack rips the ending off and tosses it into the fire. Since a lot of people are assuming Jacob and that other guy are twins of a sort, that some interesting foreshadowing.
Woah, this just blew my mind.... It could also be giving us foreshadowing of the fact that the IS NO ending... it just loops. This is a CRAZY thought, but it just might be right.