In current time, the main island as visited first by the pilot and Jin, and later by Ben and Locke is a netherworld, sort of like the realm of the dead. When they cross over by canoes from the smaller island where the Ajira plane had crashed, they are actually travelling between the land of the living and the land of the dead. This point is also hinted by Locke to Ben, immediately after he opens his eyes in the small island's Hydra infirmary, when Locke says "Welcome to the world of the living", thereby contrasting the small island representing life with the big island representing death. This theory is also supported by such facts as: Dharmaville is deserted and is shown as a spooky place and with an ashen colored filter. Dr. Shepard openly appears there without having to hide in a dark corner of the room, as he did before at Jacob's cottage. Locke moves about comfortably in this "land-time" and he seems to know! what he is doing because he has experienced death. Or, this "land-time" is a midway between a true death-world and our world, sort of like a judgment station in between, as demonstrated by Ben's trials and tribulations at the temple. We may expect to see Ceasar, and other dead losties such as Claire, Ethan, et al. on this "deathland-time" in future episodes as well. And as for Sun, she will meet her husband Jin in this deathworld, and their meeting scene will be shown back to back with Jin's simultaneous deaths both in some gunfight in the 70ies' Dharmaville and during the explosion on board Widmore's ship. Caveat: As this is pure theoretical guesswork, none of it should be considered spoilerware. Theory by stoqi
