Knowing what we know now, with the distortion of time in relation to physical objects that enter the island's bubble of weirdness.... maybe we can explain the occurrences of people that are only half there, like Jacob and TallerGhostWalt, and Wet Walt back in season 2. Maybe these people traveled improperly through the Island's electromagnetic/time-warping field and got caught between times. They flash in and out of the islands timeline and are only visible in spurts.

What about Jacob's Shack, that also seems to appear and disappear? Could it have also passed through time and got caught between zones? Perhaps the ash-like circle is some type of residue from an experiment in sending the entire shack through time.

The polar bear ended up in Tunisia. I cant see him traveling by submarine! They must have experimented with moving larger objects, like angry polar bears, and shacks.

Any thoughts on this?

I believe that there is a more direct reason for the whack-a-mole jumping shack. Hurley moved it. He has shown an ability to wish away things he does not want to see. Remember Dave? And Charlie when Charlie visits him at the asylum in a flash forward? When Hurley became frightened enough of the figure emerging from the shack he closed his eyes and wished it away. One could take this as nifty, as in clicking his ruby slippers, or creepy, as in the Twilight Zoneepisode "It's a Good Life," in which an undisciplined child has power over reality. Did Hurley encounter the bear in a prior episode? Lost brain cells fail me. If he did, he might have wished the bear away too.

I thought it was far more simplistic in the sense that Jacob just appears to certain people. I believe his cabin goes along with his illusion. I do however like the theory of Hurley being able to wish things away.

Well, thats an interesting theory willemite. Hurley wishing things away. Ben & Locke sure seemed perplexed when they saw that the shack was missing. If this is true, he should have been wishing away some Others a while back. And if its true, he must not be aware that he has this ability.

the time thing is an interesting theory, but it just dosnt make alot of sence, not yet atleast. theres nothing that has showed us there is any weird time differences on the island itself. I think it has more to do with "Jacob finds you" , not the other way around.