As I think that all the people on this site have some rockin' ideas on what could have or should have been explained re: the season finale, I am putting this task to you.
When we see MIB make his dark appearance in the foot of the statue. Jacob comes to standing position and says "I guess you found your loophole".
MIB responds "you have no idea what I have had to go through to get here"
We then see Ben kill Jacob and he drops into the fire.
As we go to the beach, we discover that MIB is John Locke and John Locke is dead.
We know only 3 rules: 1. MIB can't kill Jacob and Jacob can't kill MIB
2. MIB can't leave the island
3. It is a very bad idea to go to the light
So, we see visions of little boys running hither and yon throughout the island. They appear to MIB, they appear to Hurley and a few others.
What are the rest of the rules?
What exactly did MIB do to get to that place?
We have some ideas, like MIB being people who have left corpses like Charlie, Eko, Christian, Yemi...but please offer up some ideas!!