I'm at one of the only companies I know of outside Rackspace that's running it in production. We're doing a very poor job of it; we never hit production with any effort to upgrade the cluster in the past three years, so we're still running Havana with Nova Network.
The most likely upgrade path for us right now is VMWare 6.5.
The most likely upgrade path for us right now is VMWare 6.5.