I know people are tired of the whole ****SPOILER**** thing, especially if it is just a theory. Instead, stop reading here if you are someone who loves being naive, not knowing anything about the show, and loves being completely surprised by everything imaginable.
********THEORY....SPOILER...EVIDENCE....SPECULATION....WHATEVER*******
Originally, the final show was titled "Snake in the Mailbox", which has now been changed to "Through the Looking Glass." I think both of these are significant for a few reasons.
1. "Snake in the Mailbox" was chosen by Abrams and Cuse because of the impact and surprise that walking home, opening a mailbox and finding a snake would have on a person. Snake in the Mailbox can be a metaphor for many things, but ultimately I think it is going to point to the (not a) mole being located in the Losties camp. Combine this with the most divisive episode of the season (Expose) and you garner a lot of support for this possibility. If anyone recalls, Nikki's show (Expose) focuses on finding the Cobra - the ultimate bad guy, who ends up being Billy Dee Williams (who was perceived as the ultimate good guy). I think this episode had much more significance than we may have thought, rather than just writing Nikki and Paulo off the island. Speaking of which...according to IMDB.com, Nikki (and not Paulo) is returning to Lost in episode 21 titled "Greatest Hits" which is a Charlie-centric island. Surely, she will play some pivotal role in a flashback (unless she somehow found a way out of the hundreds of pounds of sand being shovelled on her) which I believe is going to bring the "Cobra" situation back into play - only this time on the island. Someone of great stature (more than likely one of the major Losties) is obviously going to pull the old Kansas City Shuffle and greatly shake things up. We can speculate all day as to who this may be and what may be taking place (is it a Lostie becoming an Other, a mole from Dharma (which by the way, I still believe Locke may have a great revelation to give to us by the end of season), or something else) but it is odd that she is coming back in Charlie's episode. Is he going to die at the hands of a Lostie (a la Boone because of Locke)?
2. "Through the Looking Glass" was an odd name and I went to Wikipedia to see what references are in place. Obviously, this could be a great number of things in terms of surveillance (Ben's cameras and workstation watching the Losties), or maybe it refers to "Jacob" looking on from afar (similar to the Truman Show maybe?) At any rate, on Wiki, it says that "Through the Looking Glass" is a sequel to Alice's Adventures in Wonderland. In it, there are many mirror themes, including opposites, time running backwards, and so on. I have not read the book, but we know that the producers get a lot of their ideas from literature, and if they are pulling from this book - it may be interesting to take a closer look at.
At any rate, I just wanted to spend some time speculating, as things are really building up to what I hope is not a disappointing climax to the season. I wanted to offer some ideas to chum through. Thoughts?