My coworker just came by to tell me he had an epiphany after last night's episode that, he believes, explains the whole mystery of "Lost." I've never seen the theory discussed here in quite the same way as he related it. At first glance, I don't see many holes in his theory, so I'll put it to the forum to pick holes in it. Sorry it's a bit long, but I think it's worth your time.
OK, here's the theory: Everyone DID die in the crash of 815, at least to the outside world. There was objectively verifiable plane debris, dead bodies, etc. However, the crash was caused by the magnetic field surrounding the island. This magnetic energy has a magical power that is able to regenerate any "survivors" into essentially "super-human" clones of their former selves. By super-human, I mean faster healing powers, etc. Think generally Pet Semetary, but you don't necessarily come back evil. These "new" versions of everyone are very much alive, and if they could get off the island, they could fully interact with the outside world, nothwithstanding some pretty awkward convincing of people in the outside world that you're actually still alive. These "new versions" are still human and can die (permanently), so long as their death is not directly caused by the island's "power." See Boone, Ana Lucia, Ethan, etc. Oh, the BIG catch with being super-human is that you cannot reproduce.
Dying is the perfect explanation for Ethan's comment that the last leg of Juliet's voyage to the island would be a bit "rough" or "bumpy" or whatever. He knew darn well that it would "kill" everyone making the voyage, but that they'd be safely reincarnated on the island.
Understanding this premise explains so much: (1) Claire and Aaron "survived" and are healthy now because they both "died" due to the plane crash and both were reincarnated; (2) Sun died and was reincarnated, but because she was not pregnant at the time of the crash, now cannot reproduce; (3) the FBT actually did die by crashing into the island's energy field offshore, and the version of her found in the tree is her superhuman self--that's why she will be able to heal so quickly; (4) Mikhael (the Russian, not Michael) said "thank you" when he was pushed into the security barrier because he knew he would die and be reincarnated in a higher form (and could get away from Kate et al.); (5) Juliet's sister actually was cured of cancer, as Ben promised, because Ben brought her to the island, "killed" her in doing so, allowing her (and the unborn baby) to be reincarnated as her super-self now cancer free, and then returned back to the outside world; (6) Locke regaining his ability to walk; (7) Rose being cured of her inoperable disease. The list is nearly endless.
Smokey is the embodibent of everyone's past evils. Locke was able to stare it down early in season one because he had committed his soul to becoming good. Eko, OTOH, was killed because he wavered.
The "beacon" that Ben mentions is the only way to find this island. The island does exist, but it cannot be seen unless you know exactly where to look.
OK, where are the flaws in this theory?