All I saw was a picture of Jacob in his post. I actually don't remember what he wrote anymore, but it was something along the lines of "now you're like me." I don't think I got something spoiled - I don't even understand what he said.
Spoilers for season 6 below, warning to all Lost newbies.
Anyway, I'm up to episode 14. The second half of the season has been much, much better. The scenes at the temple at the beginning were very boring. The show has gotten better but one thing really bugs me. The good guys on the island keep switching allegiances every episode. One day they're with the submarine people, the next they're with the black smoke, then back with the submarine, then back with the smoke. Sawyer and the fellas just spent an entire fucking episode planning an escape from the smoke (and in turn an escape off the island via submarine), only to have Jack change his mind and decide he wants to stay on the island. Sawyer and Jack and the fellas were traveling to the submarine camp with a boat; once Jack decided he wanted to stay, he jumped off the boat and swam to the beach. A couple of minutes later Sawyer and the fellas are imprisoned in the bear cages by the submarine folk. A couple of minutes after that the black smoke comes in and kills the submarine folk and Jack helps Sawyer and co escape, claiming "I'm with the smoke now." Is it just me or is this shit happening way too often in season 6?
My point is, these guys have known for awhile that Locke isn't really Locke, that he's an evil black smoke monster, and that Sayid isn't Sayid anymore, but an agent for the smoke monster, and still they find it prudent to trust them.
edit: Another thing: The Richard Alpert episode made my heart melt, and made me enjoy an otherwise lacklustre season (at that point). Richard Alpert is such a beautiful man, and such an an intriguing character. The episode ties off a loose end quite appropriately for my tastes (it answers the question: why doesn't Richard Alpert age?) Sure we don't know exactly why or how Jacob is so powerful, but we know he's practically a god, and that he has the ability to grant people immortality, and that's enough for me. What I like is that the gift wasn't thrown around lightly - Alpert got it as a reward for doing something very valuable, for agreeing to be Jacob's right hand man.