There was a reference to Alex... I didn't catch it, but I saw on another site that they actually showed his (or her... do we know it's a boy?) hand and arm during the confrontation with Bluebeard.

We've heard repeatedly now that the children are "safe" with the Others. Whether that's a true safety or just the Others conception of it, so far who knows. I'm thinking they may not be as evil as they seemed at first. If they really wanted to kill off the plane crash survivors, they obviously could have done so already.