If this flash-sideways stuff has you confused, you're not alone. I for one am excited that they are finally using this method of story-telling. There are two things that have come from this alternate timeline that are very intriguing.
The first is that Jack seems to be at least a little cognizant of the parallel worlds to which he now belongs. In the airplane lavatory, he sees a bloody cut on his neck as he looks at himself in the mirror. He and you could assume that he just nicked himself shaving, except this this was bleeding pretty profusely for something so small. That and Jack doesn't seem to remember ever cutting himself. After he goes back to his seat, he meets Desmond, and he swears he's met this guy before. Later as he saves a choking Charlie, he looks for the pen in his pocket, but it is mysteriously gone, and for a moment our minds run back to that first day on the beach in 2004, with Boone handing Jack a handful of pens. Do not mistake coincidence for fate. It's like pieces of other timelines have somehow made it into this one.
The second intriguing thing, one we have no explanation for as of yet, is that in this timeline, the entire island, four-toed foot, DHARMA barracks and all, has been sunk to the bottom of the Pacific. How the hell did that happen? Let's not forget that infamous shark, marked with a DHARMA logo, yet another shout-out to the early days of LOST (first appearance: "Adrift", Season 2 ep. 2). It's all so eerie.
Just a few musings on what I can now say is my favorite season premiere (save for the Pilot, of course). Have a great Friday, peeps! Five days to the next episode, and as always, click for a bigger pic.