I am basing my theory on the fact that when both Ben and John moved the Island with the FDW, they appeared in Tunisia in the "future". Yes, it has been shown that the Island has the ability to skip around in time, but perhaps naturally or by human influence, this can be controlled.
If the Island, relative to the rest of the world, is in the "past", that would explain why when John and Ben moved the wheel they appeared in Tunisia in the future - they didn't necessarily time travel, they just teleported off the island back to Tunisia which was present time outside the Island.
EDIT: I will go off into a tangent here, so just bear with me, I get back on track..
It is likely the Island isn't in the "past" but is in a pocket of space where time moves a lot slower. Usually this would mean that the Island would be physically accelerating at a very fast speed - the faster an object moves, time slows down. This was proven in 1972, they had an atomic clock on earth synced with an atomic clock moving fast in an airplane. When the airplane landed (I think it went around the world), the clock on the airplane was a tiny bit behind the clock on earth. Once you approach near the speed of light, time slows to almost a stand still.
My guess the pocket of energy on the Island has about as much energy as a super nova'd start, which is necessary to have enough energy to bend time enough to accelerate the Island to the point where the time difference between there and the rest of the world would be so different. People on the Island would perceive time passing as normal. To understand this, read up on Einstein's Special Relativity theory. This would also explain that if the energy was not released every so often, maybe it would get so strong it would totally bend timespace create a black hole (which is what a black hole does) and would destroy the world. Still, this doesn't explain how the Island is accelerating (where is it going?) or the teleportation of Ben and John.
*Back on track - Perhaps this is why Widmore is so wealthy - he was using the Island for financial gain. He could know what happens in the future and somehow use the Island to relay that information back in time. Think what you could do with the Stock Market? Remember Sawyer saying to Juliet "We'll buy MicroSoft" when they were going to leave the Island in '77?
That is a pretty good reason to spend a lot of time and resources to manipulate people and start a war just for a jungle island. Why else would Widmore want it? This could be the real reason he was ousted from the Island to begin with - using the Island for financial gain.
Will the other side want to protect the Island from being used for financial gain and power or will they have their own sinister reasons?