Right now our Gerrit server (review.openstack.org) replicates its Git repositories into /var/lib/git/ and serves them from a local Apache instance as https://review.openstack.org/p/projectname, but it also replicates the same projects to Github. Most of our developer documentation suggests cloning these from Github, but this could be misconstrued as the OpenStack Project endorsing use of Github (which is not itself free/libre software).
While developers can and do set their origin to the replica on review.openstack.org, this is a single point of failure and hosted on a server already doing quite a lot of other work. Github on the other hand is a distributed/redundant service with a lot of available bandwidth, so any solution to this should probably at least involve some minimal amount of redundancy and not add further traffic load on review.openstack.org. As a bonus, any automation which we currently point at the Gerrit server but which only requires access to officially merged change history could be repointed at git.openstack.org instead to take advantage of the additional stability and redundancy.
I think we should keep github, but listed as "one of the available mirrors" -- and use git.o.o for official links (like in LP bugs commit comments).