Pier and barracks are trashed, Christian helps Sun, smoke monster looms

Sun and Frank arrive at the main island in the outrigger canoe. The walk up the pier which appears to be run down. The lamp posts are knocked over and there is a Dharma barrel in the water. The smoke monster moves the trees a bit like in the first season. This doesn't phase Sun though who keeps moving. They make their way to the barracks that are really run down. Windows are boarded up, Dharma signs are hanging off of the buildings and trees are knocked over. Suddenly, a light comes on in one of the buildings. Christian Shepard slow opens the door and appears to Sun and Frank. Sun asks him if he knows where Jin is and he says "Follow me."

They go to the room where orientation is held and people are given assignments. The building is run down too and the "Innoculations" sign is still up. Christian goes over to the wall where new recruit photos still hang. He finds the one from 1977 which has Jack, Kate and Hurley in it. He tells Sun that Jin is with her friends. He then says "I'm sorry but you have a bit of a journey ahead of you."

The big question here is, why is all of the Dharma Initiative stuff still on the island in 2007. This stuff wasn't here when the others lived there in 2004. Did something that the Losties did by going back to the 1970s change the course of the island's history? Since there are 1970s pictures still on the wall and nothing more recent, it would seem that the barracks may not have been used since the 70s.

Also, why does the smoke monster appear to open the door of the building they are in a just hang out by the door? That was really strange.