In recent interview after the Jules Verne festival in Paris, Michael Emerson and Evangeline Lilly revealed some interesting spoilers about the finale.
Here are the details with a video:
Season 5 has two story lines that end in "cataclysmic" events and he is involved with one of the two but the more "powerful" one he is not a part of
Evangeline Lilly (Translated from French - Might not be fully accurate):
She explain that the season finale is a shock. When she read the script she couldn't believe it. The season ends with something strange and new. It is the most interesting twist in the show that has ever happened and she'll be a part of it.
Thanks to Claudio for the heads up!!
NOTE: LOST stuff is at the beginning but there are details for other shows as well after.
Posted By: The ODI