This is technically an openstack extended status thing:  http://docs.openstack.org/api/openstack-compute/2/content/GET_os-extended-status-v2_os-extended-status-show__v2__tenant_id__servers__server_id__ext-os-extended-status.html

So I _think_ (not entirely sure) that this means it's supported by openstack - I think Rackspace specific extensions start with `RAX`