I agree with Michelle. Ben clearly said that "Dead is dead". As for Jacob, Maureen, I think (but it's just a theory I have) he don't want to change things, or he would never ever have touched Locke after falling all those stories: he seemed healed after Jacob touched him. In the thread Jacob is threading at the beginning of the season finale, ther's written in ancient greek "May the gods give you wathever your heart desires". Which is something Jacob tend to suggest to losties when he meets them: to kate he says not to steal again, to Jack suggest that maybe all his father wanted him to have was a little push, so he shouln't bother, he gives little Sawyer a pen, to write to, I guess, let him make a clear breast of it.
In this frame Jacob is a good guy who loves humans (is he one too ?), wants them happy and knows that everything ends just once, but ther's before it ends the time to progress, to achieve something better, a better life.
Only one thing doesn't fit: Nadia. This threat my theory.