To be honest, I've never had an MCollective deployment Just Work(tm). It's always taken some serious debugging to figure out what the heck went wrong this time.

RabbitMQ works but is slightly problematic since the authors have a morbid penchant for not wanting to support anything but Apache ActiveMQ. Ask a question about MCollective and RabbitMQ and the answer you get is 'switch to ActiveMQ'.

Well, rabbitmq is kind of a pain to get working with it. Additionally, the modules for rabbitmq and mcollective, for puppet, don't really work that well together (read: I had to re-write the ones I found to get them working).

I'm starting work at Puppetlabs in exactly a week's time as part of a brand new "module team" and I personally promise you here and in the open that I am going to tackle the puppetlabs-rabbitmq module and fix it so that it actually works and isn't an abandoned wasteland.

Come to that I'm hoping we can start building out a full set of mcollective modules to replace the existing ones that will be fully supported and kept up to date so that getting mcollective running will be as easy as including a class and waiting.

A huge part of this job is ensuring community patches get merged in and contributors get treated as I would like to be treated when contributing to a project. I hope we can reverse your experience with modules within a few months (I took this job because I've been in exactly your position, grabbing official modules and having them not work at all!)

FYI we've spoken in the #puppet channel about just this issue ;).