If you saw the Heroes season 2 premiere you saw something very important. Apparently, after getting off the island Jack changes his name, learns he can fly, runs for congress, wins in an unethical manner, and then gives up everything to save the World from his exploding brother. What we saw in Through the Looking Glass clearly takes place after these events, but perhaps before the events seen in the Heroes season 2 premiere.
Very interesting. And more to come, I'm surprised Lost producers allowed this kind of a spoiler to be given out.