There is a good little article over at WSJ and this part caught my eye. I wonder what reveal/mystery they are talking about.
WSJ: It's hard for viewers to say goodbye to the characters on "Lost," but what is it like, personally and emotionally, for you, the creators, to have to end things?
Mr. Cuse: We'll answer that question differently in a few months. Right now, we're just in a headlong rush. It feels like the weeks before Christmas. We're busily Christmas shopping. We've got some cool Christmas gifts under the tree but we're still shopping. We're full of excitement and we're in the frenzy of planning and organizing but we know there's a certain sadness the day after Christmas and it's exacerbated in our circumstances because we know there will never be Christmas again.
Mr. Lindelof: The other night it was 10:30 at night and we were workshopping a script. We were talking about a scene of major revelation in something we've been sitting on for years and years. [In the scene] it's finally spoken aloud by someone who knows a lot and we looked at each other and thought "Oh my god, we're really sharing this?" These are the profoundly emotional [moments]. Is it scary? Is it sad? It's all these things. It's like Betty Ford admitting she has a drug problem.
Source: Full Article @ WSJ