You can see it at: http://www.wowwiki.com/US_realm_list_by_datacenter
It would be good to have the census list and also see which battlegroup they are in, what data center location they are using, ip address etc. It would be very beneficial because those then can make decisions based upon not only census data - but network data so they can pick the best server they choose to be on - e.g. least latency and also perhaps most competitive or least competitive battle group etc.
That way the list could be sortable so that you can see the closest lowest latency data centers (e.g. Boston for those in DC area), and then choose the server you wish to be on based upon stats from within the census data.