In order to ward off any premature SPOILERS, the creators of Lost taped two alternate endings to throw people off. They aired on Good Morning America today:

These alternate endings are funny if you imagine that they actually aired. Like, take a knock out season finale with a devastating final twist and then imagine that everyone was crying and scared and freaking out because Desmond came to visit them. “I’ve got to tell you, brother, some bad stuff happened on the island. You’ve got to go back.” No, that’s OK, Desmond. “You’ve got to go back, brother.” No, Desmond. “Aye.” No. “Aye.” No. “Aye.” No. “Aye.” No. “Aye.” No. “Aye, brother.” No, Desmond. “Aye.” No. “Aye.” No. “Aye.” No.