This is a great episode with a lot of drama, action and intensity. The Flashback is about Kate and why she was prosecuted by the police. We can see how Kate is waiting for somebody outside her house and then we find out that the man she was waiting for was his step-father, whom she killed at the time she leaves the house. Buuut, and this is an example of how shocking can Lost be, we later discover that the one who she killed was her real father, and the man who raised her was not her real father... yes! Very confusing, i know.
Anyway, on the island we can see how Kate is confronting an inside battle on his mind about her feelings. She hears her father on inconscient Sawyer and then she freaks out. When this happens, Jack appears on scene and, after a little talk, she kisses him, apologising and running away after this.
So... Whether Jack or Sawyer, someone she has to choose, hasn´t she?
Personally, I prefer Sawyer... Ok, Ok, not Sawyer, but Jack!!