At long last I’ve finally added the MCollective page to the wiki! If you’re not familiar MCollective is a totally amazing tool made by Puppet Labs that’s a perfect compliment to Puppet. Both are open source configuration tools but whereas Puppet is a decentralized, self-building system that works great for overall node configuration MCollective is a centralized, distributed messaging system-based tool for orchestration and direct control. Use it to fire off controlled Puppet runs, inventory hardware, or even run arbitrary commands on your systems (!).
Generally you use Puppet to set up your systems how you like ‘em and then use MCollective to actually control those systems but there are plenty of other creative uses (like building an encrypted control-channel botnet) for this tech. It’s open source, it’s free, it works fantastic, and with my guide and the Puppet Labs’ MCollective Puppet module isn’t too bad to set up either. I’ll be adding onto the “Operations” section as time goes on and I come up with other great examples of how to use MCollective yourself.