Google had slack, which mapped MAC address -> roles
Yahoo had Igor, which did nearly the same (which used yinst, which had package activation for rollbacks)
Then we saw Puppet/Chef do the same thing, except with conf files you can check in & version control.
This was reinvented again in Yahoo! for hadoop with Zookeeper, for an even shorter life-span roles. Also now with zookeeper doing elections and such, within itself.
Zynga used Zookeeper to build their own role management system, but added the Igor like features into it and started using it as an C&C master to push file/code updates with.
I see that possibly several more people will reinvent it, because these solutions start out as something simple and grow out into an feature-creep mess & then someone reinvents an easier solution, rinse repeat.
And all of them will be the right answer, except for people who are not using it :)