Not very surprising, but there is a perfect correlation between the major "junctions" and Amazon's 4 data centers spanning the world, situated in North California (us-west-1), North Virginia (us-east-1), Ireland (eu-west-1) and Singapore (ap-southeast-1).

Recently I published an article describing how we find the closest data center using GeoIP and indexing, might be of interest. http://www.turnkeylinux.org/blog/geoip-amazon-regions