sl-LOST.com has discovered some interesting things from last night's episode of Lost that I did not catch myself!
As you can see above, there was a clear outline of a woman behind Sun when she was talking to Christian in the cabin with Frank. Might this have been Claire? There's another image of this which you can zoom further here.
Also, when Frank's plane was crash landing on the island runway, the Numbers can be heard in the background! (site has audio)
These and more awesome observations, courtesy of sl-Lost.com!