Lee Smolin of the Perimeter Institute has a great seminar on time at

http://streamer.perimeterinstitute.ca/Flash/9218e873-97d5-42ba-b1c7-70e498081c43/viewer.html

His basic idea is that we cannot neglect the successions of NOWs if we try to study the universe as a whole.

http://streamer.perimeterinstitute.ca/Flash/9218e873-97d5-42ba-b1c7-70e498081c43/viewer.html