From the webpage:
Recently large-scale graphs with billions of vertices and edges have emerged in a variety of domains and disciplines especially in the forms of social networks, web link graphs, internet topology graphs, etc. Mining these graphs to discover hidden knowledge requires particular middleware and software libraries that can harness the full potential of large-scale computing infrastructures such as super computers.
ScaleGraph is a graph library based on the highly productive X10 programming language. The goal of ScaleGraph is to provide large-scale graph analysis algorithms and efficient distributed computing framework for graph analysts and for algorithm developers, respectively.
If that seems a little sparse (sorry), try the slides from the first ScaleGraph workshop. I promise it will be time well spent.
Some other resources you may find helpful:
X10 Language Specification Version 2.4
I first saw this at Danny Bickson’s ScaleGraph: a new graph processing system.