Titan exposes graph data over a machine cluster. It is an OLTP system that allows you to do local neighborhood graph traversals in sub-second time. For OLAP processing (e.g. global graph algorithms), Aurelius will be releasing two projects named Faunus and Fulgora in the coming months. These provide Hadoop connectivity and compressed in-memory representations of "graph slices." We will be publishing our talk slides tonight that discuss this eco-system of graph technologies. See http://titanbiggraphdata.eventbrite.com/

Also, Aurelius will be posting a blog post in ~2 weeks where we will be simulating Twitter. We replay Twitter from day 1 to June 2009 and slam it with ~10,000 concurrent users writing/reading follows relationships, tweets, stream constructions -- ultimately growing (what we think will be) a 3 billion edge graph when the simulation is complete.