Spread is an open source toolkit that provides a high performance messaging service that is resilient to faults across local and wide area networks. Spread functions as a unified message bus for distributed applications, and provides highly tuned application-level multicast, group communication, and point to point support. Spread services range from reliable messaging to fully ordered messages with delivery guarantees.
It has python bindings, enables thinking along Erlang lines of thought, maybe. ZODB replication(as mentioned on their website for $10k). Could be used for GridComputing, integration with ROOT, what does ROOT already provide? Limited to 128 hosts.