Just wanted to re-post this to make an additional point. In my post I say that Widmore and others want to take control of the Genie\Smoke Monster. I think this is why Widmore is back. He wants to use the sonic fence they are setting up to trap the Genie inside it and then make the Genie agree to his wishes\rules to set it free. Jacob is not lying, the Island does need protecting from people that know about and want to obtain the Genies power and that can be very dangerous for the world. I also still think that Sun packed some type of tracking device on-board the Ajira flight that allowed Widmore to track them. Could the Losties from the Alt Time Line be locked in the room on board the Sub?
The MIB/Smoke Monster is a Genie that is trapped on the Island and is controlled by Jacob. The Genie must do all of Jacob's bidding and cannot harm Jacob or anyone under his protection or those that he has touched making them a candidate to replace Jacob. I believe that Jacob came to be on this Island a long long long time ago and while there found the Genie and freed it and by doing so became the Genie's master forever, but in realizing it's power, would not allow it to leave the Island and more or less has become it's guardian until someone can figure out a way to kill or neutralize it's power. I think that one of the first things Jacob asked for was eternal life, so Jacob is very old. I think that the only way for the Genie to break its bond with Jacob is to find a way to escape the Island from which it is forever bound. I think that Egyptians put the Genie on the Island under the Temple to imprison it from the rest of the world in both Time and Space. I also think that the Egyptians created the wheel. I also Believe that Ilana is with a group of people that are trying to keep it from being discovered or leaving the Island until a way for it to be destroyed is discovered. I think that Ilana and Bram are descended from the same group of people that brought the A Bomb to the Island to attempt to kill the Genie. I also believe that Organizations controlled by Hanso, Paik, Widmore and others are trying to take possession of the Genie so they can become it's new master and have it do their bidding. I think the DI were there secretly trying to find a scientific way to either control the Genie or destroy it. I think that the Others have to listen to what Jacob says but that they also worship the Genie as a Deity. I think the jest of it will come to fruition in season 6 even if a few of the points are incorrect.