From Gizmodo:
The name of the installation is Multiverse, and it was installed by artist Leo Villareal in a 200-foot-long tunnel in the National Gallery of Art in Washingtong DC. The entire thing features 41,000 LEDs that animate and move on their own, using randomness to ensure that no one will see the same configurations twice. Multiverse will be on display throughout 2009.
Villareal "Multiverse" National Gallery of Art, Washington DC from Walter Patrick Smith on Vimeo.