I heard from Joey Gonzalez, about this project: http://incubator.apache.org/giraph/project-info.html :
"It is an open-source framework for large-scale graph computation that is community maintained (Apache incubator status), with contributors from LinkedIn and Yahoo!.
It runs on very large (4000 node) cloud systems, and does so efficiently (in memory using low-latency communication and fault-tolerant snapshots)."
"Giraph was recently featured at the HotCloud conference and has been going on a lecture circuit around the valley (...). Unlike Pegasus Giraph is relatively well designed with in memory storage, HadoopRPC messaging, infrequent snapshots, and map-only execution. Basically with the exception of startup and occasional snapshots, Giraph runs entirely in memory and communicates
It definitely sounds like an interesting project. Although no Giraph will beat our labardor! (GraphLab.. :-)