Facebook staffer Paul Butler has created this beautiful map of the millions (billions?) of friendships stored in the social network, using something that looks like edge bundles to create the beautiful map.
Butler started by using a sample of 10 million friend pairs, correlated them with their current cities and then mapped that data using the longitude and latitude of each city.
That was the easy part. Creating the right effect to show connecting relationships between thousands of cities proved to be a challenge.
Follow the link for the full-size graphic.
