Did you guys evaluate ZeroMQ? IIRC It's made by the same guys that originally designed AMQP. If you did, I'm curious to see what your conclusions were.
Yes. Among several queuing systems we played with RabbitMQ just worked out of the box with features we wanted such as reliability, confirms and the queueing patterns (routing, topologies, fan-out etc.), it was easy to use and deploy. 0MQ gave us no message persistence or broker implementation (having a broker decouples our producers and consumers), if we were to use 0MQ many features we wanted would have to written which RabbitMQ provided out of the box. I think 0MQ is more like a framework than a queueing system/platform like RabbitMQ which just works.