Wow. This jaw-dropping new video for Arcade Fire's "We Used To Wait" (from The Suburbs) is billed as an "interactive film" by Chris Milk. It plays in multiple browser windows and uses Google Maps, an address you provide, and some deeply impressive HTML5 chops to deliver an experience I've never, um, experienced before. When it asks you to type or draw a message, I found drawing to have a more satisfactory result. Just, really, wow.
As it says, this film is processor intensive -- you should shut down other programs and close unnecessary browser tabs.
UPDATE: Google posted an informative page about the various technical aspects that went into this video, many that I didn't notice: "Choreographed windows, interactive flocking, custom rendered maps, real-time compositing, procedural drawing, 3D canvas rendering... this Chrome Experiment has them all."