So. It looks like Sun, Frank, Locke, Ben and the plane crashed on the Island in the "present".
Jack, Kate and Hurley are trapped in the 70's at the height of the Dharma initiative with Jinn, Faraday and the rest of the ones who stayed on the Island.
I now have no clue whose the good guy or the bad guy between Ben and Widmore...they probably are both evil.