It's every photo taken from the International Space Station, plotted. Which is pretty awesome if you ask me. You can read more about this map over at Future Tense. And if you want to see some of those ISS shots, head over here (once the shutdown* is over).
*A word on that: Taking the government hostage is not the way to pass or repeal legislation in a democratic republic. Please give us back NASA, the CDC, the USDA, the Census, and all the other functions that should be happening right now.