Where do you see evidence of that idea?

I'm also still standing by my feeling that I think they are skipping through time based on a parallel universe or multiverse theory, both of which postulate that all times exist concurrently and moving through time would not be skipping forward or backward linearly but moving from one already existing world (not constrained by time) to another. The most reasonable mode of travel between universes on the show, IMO (based on what I've seen) would be through wormholes (which, while not general referred to in most multiverse theories, does provide a means of travel which is not rejected in the theory). In this scenario, one would in effect, exist in two places at one time since the person entering the wormhole would only "appear" to be gone for an infinitesimally small fraction of a second to the people observing (ala the movie Contact). This would also explain why "windows are only open for a finite period of time" (as Eloise stated) since one end of a traversable wormhole in physics is generally regarded as being "accelerated" or to have a higher gravitational field than the other end, i.e. are not stationary. This allows for time at the exit to have moved at a slower pace than time at the entrance (although time within the wormhole would seem to move at a consistent pace).

I once heard someone describe parallel universes as "we are all living and all dying at all times"; in other words, we are, in effect, immortal. One of the guys that writes the show said in an interview that their concept of time travel was rooted in a scientifically accepted theory.

But that's completely inconsistent with Rousseau's account of Jin disappearing when the flash happened.

The "windows are only open for a finite period of time" because the island moves. The room with pendulum tells them, "during the period of time between x & y, the island will be in this location. After time y, the island will move and we don't know where it will be." It has nothing to do with time travel. There has been nothing that says the island itself travels in time, it seems to be moving in space instead.

ABC.com.

I think Lost is probably the one show you don't have to worry about ending abruptly. The small revolt from Jericho viewers will look like child's play compared to the revolt from Lost viewers if they randomly pull the plug.

Not necessarily. Insofar as I know, the people moving through time on the island are only moving through the past. I have never read anything in this theory (although granted, my knowledge is limited to a layman's study) that says people in the past would experience a time/space traveler as a permanent fixture. In my understanding, all times/spaces already exist as do the people and things in them. Someone moving from their own current universe would only occupy another immutable universe for a fixed period of time before moving on to another, or back to their own universe. I also accept the idea that even if this is the overriding theory that they are using, they are not above tweaking it for their purposes.

Parallel universes/multiverses allows for space/time travel. It is still, technically time travel because all times (and places in time) exist at once, including all possible current times. In this theory, the island's movement through space would be the island moving between many possible current times.

As an aside, if you remember at the Orchid station, on the instruction tape, Marvin Candle said the station sat on a store of "exotic matter". Morris-Thorne wormholes are postulated to be held open (or stable) by a form of "exotic matter".

IMHO, you're adding an extra crunchy layer which the show doesn't have any real evidence of, and doesn't answer any questions. Sure, all things are possible. But why try to make it more complicated? ;)

I just got all caught up on Fringe and I haven't caught a single Lost reference. Can you give me some examples?

The only one I've caught was an Oceanic Airlines ticket that was in someone's apartment. There are apparently a lot more.

I just found a LostPedia entry that tries to flesh out the overlaps between Lost and Fringe. Other than the Oceanic Airline ticket and shared cast, everything else is really a stretch.

It's my understanding that Oceanic Airlines is not unique to Lost.