Well, I was watching the finale yet again, and I was wondering about this. It seemed a little out of character for Jin, previously so protective, to be ok with Sun, now pregnant, going with him on a boat. I mean, I realize the couple had just recently "had it out" about Jin's controlling nature, and he had become more understanding of her will... but they were in for a possibly a dangerous mission where they might encounter the Others. I just thought it was a "conventient" plotline to have Desmond turn down Sayid's request to help him sail, and then Jin just happens to be the only one he can ask--was it a way for the writers to get Sun on this boat?
In other words, have her written in that way so that the only pregnant woman on the island is somewhere "needed" for the plot. I was thinking either distance from the electromagnetism, or maybe proximity, to be captured by Others?
Or maybe it is nothing at all.