Bike path in Santa Monica, California – May 18, 2009
This is called a follow pan. You move the camera to follow the moving subject. I used a slow shutter speed (1/8 second) to really blur the background and show motion.

For those that don’t know about this famous bike path, the South Bay Bicycle Trail runs along the Santa Monica State Beach. The Trail stretches 22 miles (35 km) – north towards Malibu and south to Torrance – and is the longest beach path of its kind in the world.