**SPOILERS... DO NOT READ IF YOU DON'T WANT TO KNOW SHITLOADS**
Desmond forgot to push the button, so that's what caused their plane to crash. It's like some kind of EMF type of deal. Now that Locke didn't let them push the buttom, the EMF went insane again, and Desmond's woman had those guys looking out for some kind of EMF disruption. That has to do with the "I think we found them."
And the people who said they hate Michael, I think your wish has come true. It's rumored that he sold his condo in Hawaii and he moved to LA. I don't know if that's just for the summer, but I think him and Walt are saved. That one guy let them go and they're supposedly going to get rescued.
I heard a rumor that season 3 is going to have new arrivals. I don't know if they're already supposed to be on the island, or if the EMF malfunction caused another plane or boat to get trapped into their portal. Oh, and by the way, they're in the Bermuda Triangle or something of that sort. JJ was interviewed and he was asked about the Purgatory/Bermuda theories, and he said that the purgatory theory was one of his favorites, but that it wasn't true. He didn't comment on the bermuda triangle theory. The "Others" are actually scientists with Hanso, conducting experiements. Hence the fake beards, etc.
There's a whole Lost webgame going on @
http://www.thehansofoundation.org/The website was advertised as a legit foundation in a commercial during airing. If you were to just go there without knowing it's a game, it's pretty convincing. It's insane, it shows a bunch of active projects of the Hanso Foundation, which is supposedly who funded the Dharma Initiative. If you go to the Wellness and Prevention section and click on the maps, there's a hidden link showing that they have projects going on in the bermuda triangle.
It's all just an advertising ploy for conspiracy junkies, but it's pretty interesting. They even went as far as interviewing Hugh McIntyre a fictional Hanso executive on Jimmy Kimmel Live...
http://lost-media.com/modules.php?name=Downloads&d_op=getit&lid=580A few people I know honestly believe that it's real, but it's all just a big joke. ABC is trying to pawn it all of by convincing people that Hanso is real, and that Dharma Initiative is still going on, and not discarded in 1987 like they stated.
http://en.wikipedia.org/wiki/The_Hanso_FoundationIf you're bored, go to the webgame and see if you can crack some codes.