When a dead body lands on the Island, the Smoke Monster inhabits it. When Christian Shephard landed on the Island, the Smoke Monster took over his body. In "Cabin Fever", when Christian claimed to be speaking for Jacob, he was lying. In reality, he had somehow "gagged" Jacob. The purpose of this was to tell Ben and Locke to move the Island. This was NOT what Jacob wanted. The Smoke Monster knew that Locke would eventually die, and come back to the Island as a dead body. The Smoke Monster planned to take over his body, and then assume a position of authority with the Others. The Smoke Monster is the antithesis of Jacob; they are the war that Widmore referred to. The master plan of the Smoke Monster the whole time was to become the leader of the Others, then to kill Jacob. Perhaps the Smoke Monster cannot find Jacob on its own, perhaps it cannot kill Jacob on its own; it is not my place to speculate. But I am so su! re that Season 6 will be the story of the war between Jacob and the Smoke Monster. Perhaps the end-game is the fate of the Island, or more likely the fate of the world.