One of the reasons that I love this show so much is because no charcter is safe and when they kill someone off it's for good. Except for Jin. And people that appear to Hurley. And probably Juliet next season. But I digress.
I'm sure that Jacob will be prominant in flashbacks next season but I think as far as the current 2007 timeline goes he's dead. Hopefully for good. Along the same lines I'd hate for the creators to cheapen everything by bringing back certain characters next season just because a few chicks really love and miss Charlie.