I can't wait to see tomorrow's episode. I love these mind-bending future episodes.
Procutus: the reason why Walter hasn't aged is because according to one of the sneak peeks of this episode, Walter has been encased in the Amber material for 20 years. You can watch that sneak peek and the others here:
http://www.spoilertv.com/2012/04/fri...transit-3.html.