On the Tuleap blog there's an article posted showing how they made the switch from RabbitMQ to Redis in their PHP application.
There are various places in Tuleap were message queues are needed but the primary one is to run jobs in background. Historically it was for all system related stuff (creating users, git/svn repositories, etc) that required special unix permissions that we were not eager to grant to a web app.
[...] More recently we add a need to share events across servers, for distributed Tuleap setup for instance. Our good old system was no longer able to deal with that because we needed a real queue management that works across servers. We choose RabbitMQ because we were looking for a queue system, PHP support quite decent and tutorials were good. However, we had to setup a quite complicated queue system.
The post outlines the exchange to exchange binding system they created and includes the code use to make the RabbitMQ-based system work. Then they introduce Redis and how, when they learned about RPOPLPUSH, decided to make the switch. The code for this replacement is also included.