I think there's definitely something uncanny about being able to look a dead person in the eyes. It's not so much the recognition that everyone will die as the ability to simultaneously see them as a living being and know them to be gone. Granted, it's debatable whether photographs actually do anything new in that regard. I get the same uncanny feeling when I look in the eyes of the Hellenistic Egyptian mummy paintings:
http://commons.wikimedia.org/wiki/Category:Fayum_mummy_portr...