If you haven't figured it out already this is yet another great episode with subtle character development undertones throughout.
First, we finally get to meet Locke's mysterious Hellen, and reveals to us how she saved him from himself and his suppressed rage against his father's betrayal. She proved to be Locke's salvation, as he was searching for hope. This explains why Locke screams at Jack that "it was never easy" having faith and why he "can't do it alone". However, this also brings up new questions. Why wasn't Locke with Hellen when he was handicapped? Was there some sort of accident that crippled him and killed her? Is that why he calls phone sex lines and speaks to another "Hellen"? Was he having problems letting go of his emotional/spiritual rock?
Secondly we learn that Jack has SERIOUS emotional baggage when it comes to his former wife. While it was never explained what happenned to that marriage it plains to see that Jack is freaked out by the subject. Did she die? Did they divorce? If so, did Jack leave her or vice-versa? This trauma plays heavily into why Jack takes out his rage/frustration on Desmond. Does he feel that Desmond is somehow resposible for Jack marrying the girl in the first place? After all, it was Desmond who convinced Jack to go back and talk to her.
Lastly, we learn of Anna-Lucia's fate. You remember her. The girl that Jack spoke to at the airport bar before the plane crash in last year's season finale. Yup, she's alive alright, and she (alongside with several other mystery people) have got Michael, Sawyer and Jin hostage. Is she part of the mysterious others or just another lost survivor?
Personally, I think she and her crew are all survivors from the rear of the plane. They didn't fare as well and went all "Lord of the Flies". Why do I think this? Well to start they all look raggady as hell. Secondly, they have clubs for weapons. (The others on the boats had AK's.) Lastly, I think it would be a great plot twist of the big burly black guy Sawyer nicknamed Shaft was Rose's missing husband. That would be SWEET.
A great show with a great plot. Keep 'em coming.