I'm starting to lean towards the theory that they're all inside a computer simulation called the "Matrix" and that John is the "chosen one" who will defy the laws of physics and fight an "Agent" and eventually score with the hot brunette, while saving the rest of the world by kung-fu fighting in slow-mo to Rage Against the Machine songs.

Just a guess.

Well, this season finale is looking like a real time must see TV moment...and there haven't been too many of those this past year with the strike and all.

Have to agree with you that Daniel is the other time traveller along with Desmond. The show has it's share of central characters who are superficially opposites but who have similar 'powers' as it were. Locke and Ben, Jack and Sawyer, Desmond and Daniel possibly too.
Does moving the island mean physically, or temporally? It's already out of synch in both regards. Does Ben think he's going to move the island to the artic, and then end up in the desert wearing the parka?
Does anyone else find it kinda silly just how great a tracker Kate has become? I almost expected her to put her ear to the ground and tell us how many people were stalking them. Do you think that the writers (who are usually a smarter bunch than that) have a plan about all these 'superabilities'? Everyone on the island seems better at things than they would or could be in their earlier lives. Not to put too fine a point on it, but doing solo spinal surgery with iffy antisepsis on a bony tumor encasing the spinal cord is .... well.... more than a little unbelievable.
So, a question about the numbers and the first hatch. When they stopped plugging in the numbers and that hatch/complex exploded, what impact did that have on the island? Did it allow people from elsewhere to find it? Didn't that happen when Desmond messed up at one point, the alarms went off and the Oceanic plane 'found' the island?
Another thing. I'm confused about the time difference between island time and real time. Time on the island moves slower, right? Or, is it just out of phase, but passing at the same speed as the outside world? That long midseason break did not help my comprehension here......

@Boomer - From what I've gathered, time on the island is simply "out of phase" with the rest of the world, and they never really state by how much. It seems like that if you enter the island by Daniels coordinates you arrive at the correct time, so at bearing 305, time is 1:1 (meaning time is equal).

But as we've seen, if you stray from that bearing, time differs anywhere from a few minutes later (like the rocket sent from the freighter to Daniel) to a few days earlier (the doctor's body washes up days before he's killed).

So here's my crazy theory: the island is surrounded by a curved electromagnetic bubble. At 305, you're entering it at a straight shot, so there is no time difference. At 304, you hit it at a slight angle so you arrive on the island in the past by a small fraction. Conversely, at 306 you hit it at a slight angle the other direction so you arrive on the island slightly in the future.

Because space and time are bound together (Einstein called it spacetime in his special relativity and it was further expanded upon by a certain scientist named Hermann Minkowski), there might also be some spatial travel involved as well as time travel. For instance, Desmond may not have been able to sail away from the island because space kept curving around, landing him in the exact place he left. Only by hitting it at a perfectly straight shot, can you leave the island at the exact time.

This might also explain another little mystery that's been plaguing me. Daniel reveals the coordinates to be 305, but when Ben lets Michael go, he gives him the bearing of 325.

If the above theory is true, Ben may have given Michael an incorrect bearing on purpose. At 325, Michael may actually have arrived in the real world slightly in the past, which would explain how he left the island, sailed back to civilization, hooked up with another boat, arrived back in America, got a car, a house, a job, met with Tom, etc... a ll within the extremely short time frame before he arrived back at the island this season.

I think the hatch was a maintenance measure for the electromagnetic bubble. By keeping it under control and venting the EM energy every 108 minutes, maybe Ben could accurately control how much or how little the island was out of sync with the rest of the world. Maybe every 108 minutes, they'd send the whole island back 108 minutes so that it stayed in the same place and time forever. Either way, when Locke blew it up it released a lot of energy. Maybe it rocketed them forwards in time to where they're supposed to be - that would explain why it suddenly showed up on the arctic screen and why the sky turned purple. The sky is blue because that's the wavelength of light that our eyes detect filtering through our atmosphere. Speed up time, however, and the wavelength gets faster as well, so maybe we'd see purple instead.

It's a lot to theorize about.