A few thoughts after reading this thread and watching the finale again last night:
When Ben is giving his "What About Me?" speech he says something like: "And when he asks to see you, he gets marched straight up here as if he were Moses." Then the screen shows Locke 2.0 making a little smirk. I'm not sure what to make of this Moses reference yet, and how it fits into the Jacob/Esau mythicism, but I thought it was noteworthy.
Jazzy - You could be on to something here. There's a part in the penultimate scene, I think where Jacob says "I see you found your loophole" then they cut to Locke 2.0 where I faintly heard that trumpet-like sound you hear when the smoke monster attacks.
Later, when talking to Kate, Jack says about exploding the thermonuclear device that: "nothing in my life ever felt so right." This indicates that Jack doesn't fully understand his role and that destiny or fate is exerting itself.