Go no further if you don't want to know what happened (or may have happened).
Roughly two months — or, more accurately, two TV seasons in real time — after Oceanic flight 815 crash-landed on this lost tropical island, viewers learned:
"There's no outside world, there's no escape," he wailed, drunk and despondent, when the castaways retrieved him from the sailboat just offshore.
So the audience learned that the button really did need to be pushed, and wasn't a meaningless exercise after all, which became a season-long issue that on the finale fueled a raging argument between Locke (the disillusioned former believer) and Mr. Eko (the fiercely loyal convert to the button-pushing cause). After an explosion in the hatch, they were both unaccounted for.
After having been brainwashed by the Others, Michael had gunned down fellow castaways Ana Lucia and Libby a few episodes ago to facilitate the escape of Henry, an Other from across the island whom the castaways had been holding captive.
Then — despite the best efforts of Jack and Sayid to outmaneuver him — Michael made good on his plan to deliver Jack, Hurley, Sawyer and Kate to the Others in exchange for Walt.
Hurley was released by the Others with an order to return to camp and warn the rest of the castaways against retaliating.
"But what about my friends?" Hurley protested.
"Your friends are coming home with us," said Henry, the Other who had been held in the hatch.
While Jack, Sawyer and Kate looked on, bound and gagged, Michael and Walt were given a motor boat to make their safe escape.
"My hunch is, you won't say a word to anybody," Henry told Michael as he sent him on his way, "because if you do, people will find out what you did to get your son back."
"Who ARE you people?" asked Michael, voicing the question that has plagued "Lost" viewers all season.
"We're the good guys, Michael," Henry said simply.
Disinclined to argue and at last reunited with Walt, Michael piloted his boat to apparent freedom.
Hoods were pulled over the heads of Jack, Sawyer and Kate. Their safety while in the Others' custody was assured by Henry. But viewers will have to wait until fall to see.