Quoting from workspace news:
The STAR community successfully completed its first production-size deployment of a VM-based virtual cluster managed by the workspace service and backed by EC2 resources.
The 100 node cluster was composed of a headnode and workernodes based on the OSG 0.6.0 grid middleware stack and Torque. Its deployment-time configuration was securely coordinated by the new workspace contextualization technology.
[UPDATE, related: http://www.gridvm.org/virtual-cluster-appliances.html]
[UPDATE, see: One-click clusters, VWS TP1.3.3]