This picture shows the satellite Iridium32 reflecting sunlight as it passes 490 miles overhead, travelling 16, 695mph. As it has since September 14th, 1997.
Iridium satellites give particularly bright reflections. The original plan was to have a swarm of 77 satellites for mobile phone use, with orbits designed so that at least one would be in the sky at any time. A satellite phone would then work anywhere on the planet provided the user had a clear view of the sky. The name comes from the fact that the element iridium has atomic number 77.
Unfortunately, the network was not a commercial success and the whole operation was sold to the US military.
The reflections can be seen as bright points of light, travelling faster than a high-flying aircraft, and can easily be seen if you happen to be standing in the right place at the right time. To get information on seeing these yourself, check out the excellent web site Heavens Above.
Iridium flares appear on long exposures as diamonds as the point of light gets brighter and brighter then fades away again.