In this New York Times article about the resurgent usefulness of the U2 spy plane in Afghanistan, this tidbit about this plane from the 1950s Cold War era made me go "woa."
Marine officers say they relied on photographs from the U-2’s old film cameras, which take panoramic images at such a high resolution they can see insurgent footpaths, while the U-2’s newer digital cameras beamed back frequent updates on 25 spots where the Marines thought they could be vulnerable.
The U2 can also fly at twice the altitude of a commercial airliner. From that height, you know whose footprints a U2 pilot can spot without the aid of its fancy cameras? Yo momma's.