I heard someone here mention this a while ago, and more and more I'm beginning to agree with it. Theory goes that all of the characters are going to be brought to one place for a specific reason (what that reason is I have no clue, maybe to merge the time lines.
In the OT it seems to be Locke's camp. that or maybe it'll end up being Hydra island. What I find more interesting is the FST. Claire is in the hospital that Jack works at due to pregnancy issues. Charlie is in the hospital after driving into the marina. Jin and Sun are presumably on their way after Sun was shot. Locke will inevitably end up there. Sayid might end up visiting his brother in the hospital. I'm guessing Ben might be called to the hospital because he was a witness to the attack and can give doctors a better idea of Locke's injuries. My guess is that there will be some sort of chase with Kate that leaves her injured and Sawyer has to take her there. Maybe Rose's cancer acts up? No idea how Hurley might make it there.
I'm just guessing that there is a greater reason for why all these characters are arriving at St. Sebastian's. Plus there seemed like there was implied significance when Desmond was talking with Jack, saying Charlie was there too. Jack said something like: "Wait, there was someone else from our plane? An he's here in the hospital too?"
The way Jack said this seemed as if he knew, or at least felt some significance behind it all.
Or I could be completely wrong.
And total side-note tangent. Anyone else really liking Giachinno's more recent music in the last episode or two? It has quite an epic purposeful feel to it.