October 2, 2010 was "Nuit Blanche" in Paris, or 'White Night'. Nuit Blanche is sort of like an all-night party in Paris that celebrates art, and in this sense especially uses light to display it. Installations are set up around the city, often centered around white/light, and are there or running all night long. It's been happening for a few years, and is now copied in other cities around the world.
After the "Fete de la Musique" this summer in which nearly every street corner had music acts performing, I had high expectations for Nuit Blanche. But to be honest, I was a little disappointed. The art was not nearly as plentiful or easy to find, and a lot of the displays were indoors, with waaaaay too massive of lines outside for me to wait in. I much prefer stuff that's just out in open air, and those seemed to be very few. Instead, it was massive amounts of people wandering around and not finding much. It was a very good night for the few musicians that took to the streets, because they drew huge crowds or bored wanderers who weren't getting their entertainment fix through the art.
I did however walk by this gem (thanks for the tip, David!). It was very cool and much fun to see in person.