Well, ideally it would be from this year...but hey, what the heck, it was a gaming moment from this year, so why not?
Crap, forgot to include my top moment(s). Personally, as much as I've wracked my brain, I keep coming to Bioshock. I love those atmospheric, eerie adventures and Bioshock fit all that and more. The sounds of the ocean surrounding you, the history of that doomed city...all of that and more made for an incredible experience. Yes, the latter half wasn't quite as good, but it still was my highlight.
In a very close 2nd place, seeing the sun rise in Crysis. Combined with the ambient jungle sounds around me, it was my prime reason to continue upgrading my system for PC releases of next year.