Electroland‘s EnterActive (11th & Flower) project at 11th and Flower Streets in downtown Los Angeles consists of a luminous field of LED embedded into a facade and controlled by pedestrian traffic into the building.

Environmental intelligence and surveillance of human activity are combined with a video-game sensibility. Activities on the walkway also trigger massive light displays on the building face. When the walkway interactivity is triggered users witness their impact on the building face via a video display.

Quicktime video.

See also Kinecity‘s project for 7 World Trade Center that uses camera based recognition systems to activate facades, tunnels and interiors.

Via Information aethetics and Computing for Emergent architecture.
Also by Electroland: interactive walkaways.