I'm a few weeks behind you lot, and a few weeks ahead of Aus/rest of world, so forgive me for being on my own timetable here.
Wow, though! Theories are: 1, Jacob is Christian. Jacob/Christian is the dead dude in the coffin. Now, before anyone laughs at such a far-fetched idea, bear with me. The visions the Losties have had on the island have all so far been from people who are still living, no? Locke seeing Walt, at least. Not too sure about Kate and the horse she saw...
Jack saw his father in an earlier season, chased him, never caught him. He did ID his body in the morgue, but why was the coffin on the 815 flight empty, and where was his body in the wreckage? Is Christian really dead at the end of season 3? I took the photo one of you posted of Jacob and played with it a bit. After a while it began looking like Christian. But it also looked like the man who walks his geriatric Cattle Dog up the road from me. Ah, who knows. The father thing fits in some ways, though, being a guy no one had any lost love for before the flight and crash. The person Jack phoned tearfully might have been his mother. No? "Mum, I've just read... I'm sorry", etc. Christian is a strange character. Always found him very curious as well as bloody irritating. Also worth musing over is the guy in the chemist where Jack is trying to get his 'script filled says "Give him a break! He's a hero twice over" Once for the lady who he saved on the bridge, but the other time must be for something he does to help get them rescued, surely? If you're going to give great credit at this stage (end of season 3), then surely Charlie is the hero award winner. What will Jack do which gives him 2 hero statuses? Has to be something worthy of publishing, and for a guy in the street (so to speak) recognise him. Obviously, the return/rescue of the Losties will make huge news because the wreckage was mysteriously 'already found and there were no survivors'.... Was this Naomi who told them this, now that I think of it? Hmm, maybe strike that as credible in the storyline... She's as full of dung as Juliet.
Anyhow... Kate I reckon is pregnant, end #3, and in the airport scenes with beardy Jack has since given birth and is trying in vain to live a normal life with the chameleon Sawyer (the father). If Kate is not living on the island, would that ensure she lives through childbirth? That could explain her lack of interest in returning. She is pretty adamant. For a girl who was on the run to now refuse point-blank to return to the one place no one could find her?... What makes gyspy Kate now desire such stability? We shall hopefully find out.
Apologies for bumping this thread, by the way. I only saw the last 4 eps last night, so I'm still digesting it all.