I live in Crow City, USA (AKA Monterey, California).
I can't tell one crow from another without their perching right next to me on a bust of Portola. They seem to all be clones of each other, as far as I can tell (and I'm sure that's true of most non-ornithologist humans). Yet crows can differentiate humans one from another.
This (presumably) does not prove that crows, clever as they are, are more intelligent than humans, but does it indicate that they are more interested in us than we are of them? If so, why? Or what is the reason for this gap in observation skills?
Some humans are birdwatchers, but it seems all crows are people watchers.
This corroborating link (Friend or Foe? Crows Never Forget a Face, It Seems from The New York Times, Aug 25, 2008) was provided by a cat who had a hard time adding it for some reason.
An article published by the National Wildlife Society on November 7, 2012 describes that study, as well as results from other research. It goes into more details explaining that crows and other birds do recognize us, and potential reasons why. It also has links to more information about crows and other birds in general.