OK. I can't believe I'm posting here.. I've been an avid reader for years now, and luckily there have been some fine people posting solid theories and opinions so I haven't really felt the need to write anything.
That being said, here are a few thoughts after last nights episode.
1. Kate's name not being written in the cave.
Somebody has already posted that Kate is the 'wildcard'. I think this is correct, but I'll take it a step further. I think Kate is there to influence Jack and Sawyer. She was brought to the Island to sway Jack and Sawyer (arguably the two super-power personalities on the island ...besides Locke who is in a league of his own).
the question: Why did Jacob bring Kate to the Island if she's not a candidate? she must have a purpose. That purpose is to be a catalyst or an influence on the two people who are the most stubborn. Jack and Sawyer.
2. I doubt that the writers on the show would make a mistake.. but... why is Jack's name on the cave? Didn't Mr. Friendly say in Season 3 "Shepards name isn't even on Jacobs list!"
could Shepard mean Christian Shepard?
OR
could there be two lists, and the Others have been taking orders from the wrong guy all these years?
Is it possible that Jack was always on Jacobs list, and that Ben and the Others were following MIB's orders unknowingly (since Ben could never see Jacob)? and Jack was not on MIB's list?
I know there's a lack of detail, but they are some new thoughts I'd throw out there.