I had this experience when copying a group picture originally taken at my grandparents' wedding with my own modern camera a few days ago. It was quite an odd feeling when the camera picked up all those 100-year-old faces and I could hear myself saying, 'Now everybody smile ...'
Another unexpected face recognition moment happened recently when I was idly looking around the Mount Rushmore area of South Dakota with Google Streetview. I'd just been reading about the building of the famous monument and wondered what it looks like from the local roads. And guess what ... on many of the Streetview images the face recognition algorithm at Google has spotted the faces of the four presidents up on the side of the mountain and dutifully smudged them out to preserve their anonymity. It turns out that the software is fallible and depending where you place the camera around the area, different presidents are concealed and revealed in turn. Try it yourselves if you have nothing better to do for ten minutes.
-R