Lost: Desmond Theory

I know Lost's phenomenal Desmond episode is now two weeks in the past (but what is the past? ;-)), but I just got this blog up and running so here is my theory two weeks late.

In a word, I believe Desmond's episode is the key to how Lost is going to end.
 
While it never explicitly said so, I felt that the episode alluded to the fact that Desmond's "flashback" may not have been a one time thing. I believe that he is, in fact, caught in a loop.
 
With that in mind, the show did explicitly discuss another topic: Desmond's destiny. The show made it very clear that his destiny is to be on that island to turn the key. It was also very clear how he was to get to the island, by participating in Penny's father's race. Therefore, once he turns the key, he has fulfilled his destiny. The only problem is, he's now stuck on an island.
 
Which brings us to the last minute of the Season 2 finale, in which two people who are monitoring for a "signal" make a phone call to a woman to tell her they "found it". And who was the woman they called? Penny.
 
So my theory is that, in one of his "loops", Desmond is somehow going to convince Penny that, while he loves her, he must fulfill his destiny of turning that key. But, as I mentioned, once he turns it, his destiny will be fulfilled and they can be together. Obviously, when he turns the key it is going to emit a pretty significant "pulse". So all Penny has to do is use some of her father's money to set up an outpost to monitor for the signal, which will lead them to the location of the island and, viola, The End.