Google's autonomous cars are everywhere, having logged nearly 200K miles of driverless miles in all sorts of conditions. There's a bunch of technology in there powering the system (embedded link has some cool video presentations):

• a Velodyne 64-beam laser for creating detailed 3D maps of the environment
• four radars to detect traffic
• cameras to detect traffic lights
• GPS
• an inertial measurement unit & wheel encoder

There was a lot of learning to program into the cars based on modeling human habits and showing a bit of aggression to avoid the algorithms constantly yielding. Google's next goal? Getting a threefold increase in safe miles by hitting a target of one million miles.