Data centers in used nuclear bunkers aren't new - www.thebunker.net has done that for a decade in the UK. They found that having a cool-looking site made it easy to sell to bankers who wanted reassurance about physical security, and at least with the computer technology of the time it was easy to do HVAC, since the place was naturally cold, and they had good redundant power grid connectivity to work with. As far as the risks of publishing the location of your data centers go, I've generally been on the pro-publishing side; real attackers would *never* think of looking for the large building downtown with no windows, or looking for a data center business named "One Wilshire" near Wilshire Blvd (:-) More seriously, though, many customers need physical diversity for their circuits, and while it's more reliable to get that from a single fiber carrier than try to get predictable diversity from multiple carriers, there's still a need to do some auditing. Of course, if you've got a bunker already, it's pretty cheap to get your CEO a monocle and a white cat, whereas if you're starting with the monocle and the cat, getting a bunker can be fairly expensive.