I run a bunch of box under OpenBSD at $WORK and I wanted to be able to run mcollective on these too. Unfortunately, there were no package available for this OS. So I took time and with some help from landry@ I was able to build a port. It has been integrated into the github repo quickly. But to be able to use mcollective you also need to have the ruby stomp connector. As I don’t like using gems and prefer them packages, I also built a port for it. You can grab it in my github repository here.
These packages have been tested under OpenBSD 4.7 (i386, but they are no_arch ones, ruby related), let me know if they work for you.