I'm working on releasing one of internal modules as open-source as I think it can be beneficial to others. The module is a ZeroMQ / pcntl / ZF2 background processing system with EventManager like API dubbed "Proletarier".
The code + documentation + some samples are here:https://github.com/shevron/proletarier
It's in early stages but already works well for us. I'd be very happy to get your feedback and thoughts. Contributions are obviously welcome :)