Shannon's dad IS the person who in a wreck with Jack's wife. They showed that on an episode awhile back. Remember when Jack had to choose between saving his future wife or Shannon's dad and he chose his future wife?
Editing to add, I am not watching Lost right now because I got home at 5 minutes after 9, now I have to wait for it to finish taping so I can watch from start to finish! I can't wait to see what happened to the tail enders!!
