I'm with Jollydwarf on this on this. The actor playing Ethan looks at least 40 years old, so to guess that he was the mystery baby would have been a stretch.
I thought this was one of the more "human" Christian encounters we've seen, and by that I mean he didn't seem like a guiding spirit. He actually came across quite human, turning on lights, physically taking the photo off the wall, and actually not disappearing when we all probably expected him to.
Related to this encounter, it appears the barracks are still in shambles from the 2004 assault by Widmore's men. It was a pretty cool reality check, though, when Sun and Lupidis docked and saw that the area was in disarray. For a moment, I'd let myself believe they'd all landed at the same point in time.
Anyone have a theory as to why Sun wasn't pulled into 1977 with the rest of the Oceanic 6? Geez ... or Locke, for that matter, or even Ben or Lupidis? Are they meant to "go on a journey," as Christian implied?
I was kind of disappointed to see that Daniel did not turn out to be Radzinsky. Instead, Radzinsky kind of turned out to be a prick. That was a major letdown. I am interested to find out what Sawyer meant about Daniel when Jack asked about him.
There's was a little Easter egg in the epsiode, too, that I read. Sawyer asked Juliet where his big sweatshirt was, and it ended up being the one he gave to Hurley. It was a Georgia Bulldogs sweatshirt, and that's apparently where Josh Holloway went to college.
Oh, and the Lostpedia entry says that Jorge Garcia's girlfriend was one of the survivors from Ajira 316. The pretty one shown standing behind Sun on the beach.