We saw Jacob last in Ab Aeterno, but that was the 1860's. Ok, it is arguable that he was impersonating Isabella, but you have to go right back to Lighthouse to find Jacob actually doing anything to progress the OT current storyline, and to do anything to influence the fate of the candidates. I know the guy is dead, but that seems to count for diddly squat on the Island. There is a war going on, and he seems to have absented himself from all this. All of this 'Jack needs to stare at the ocean' crap, has left Jack in a complete & utter quandary. He has trusted Hurley, then he trusted Sawyer, and he is now in FLocke's hands. Is this all part of Jacob's plan?
Given that he was the one who brought the losties to the island, and famously told Richard that if the MiB leaves then the island pops like a cork and evil escapes, then where the hell is he, and what is he doing which is so important that he can't even show up to give Hurley any moral support?