Facebook engineering commented on its in-house implementation of Web Scale change propagation messaging infrastructure called Worm Hole. Essentially it Tails on a DB / FS updates and publisher propagates them over streams across data center.
It seems to support some basic messaging Properties:
1. Reliable In-Order Delivery
3. Low latency
with some web scale abilities:
1. Data Partitioning
2. Rewind in Time
Facebook engineering Listed Advantages as:
1. Volume: Wormhole processes over 1 trillion messages every day (significantly more than 10 million messages every second).
2. Ability to deal with failures
3. Ability to scale up / down
4. INtegration with monitoring systems
5. Cache synchronization across data centers in a shorter span
6. Lowe consumption of resources (Quoate: Compared to the previous system, Wormhole reduced CPU utilization on UDBs by 40% and I/O utilization by 60%)
This is not yet open source.