Interesting. So I was about to write this off as a somewhat "light" episode, but the more I think about it, the more I think it was a pretty powerful episode, if more for the subtle things it revealed. But before I go into that, let's cover the facts.
First off - the show focused on the Koreans, Sun and Jin. I'm always happy to see episodes focused on them, but I kind of have a soft spot for Koreans. We find out that Jin was infertile, yet somehow Sun is now pregnant. It was kind of hinted at that she may have cheated on Jin, but it was never outright said/shown that she did.
The other main plot of the show was Ana Lucia (sp?) interrogating Hale. He draws her a map to his balloon, and the last we see of her, Charlie, Sayid is them arriving at the supposed crash landing of the balloon.
Now - this is what I'm thinking. I've talked before about how I think the theme of this season is the breakup of the group. This is demonstrated in the obvious split between Jack and Locke, and Charlie being ostracized from the rest of the group. At the end of today's episode (am I the only one who laughed out loud at the Dharma cereal? I'd kill for a box of that), Ethan once again proves to be a troublemaker, revealing that he drew a map for Ana Lucia and how he has noticed how much Jack and Locke are fighting. He also makes sly humour about how if he were one of the Others, the map he drew would have led Ana to her capture, so that the Others could trade prisoners for him.
I'm really torn. My past theory (the Others were scientists trying to rescue the real "Lost") is really blown I think, now that we know the Others are Dharma actually. Other people have said the maybe this is simple a big experiment. I think this seems like a real possibility, especially with the Others being nothing more than Dharma in disguise. However, in the last episode, a part of me really felt like Ethan thought there was a real virus out there, and that he was really helping Claire. Maybe it's an experiment inside an experiment?
Anyway, as I mentioned, I did create a Lost forum, and you may want to post your comments there. Or here. Either is just fine.