I've been to lots of them all over the world, names you'd recognize, and they've all had 48V.

Facebook's Open Rack project is based around 48v.

It's pretty common here (nl), you have to ask for it but it is usually available. I'd advise against it because you're deviating from the bulk but if you need it you can usually get it, especially at the larger colocation facilities.

Yes they do. My old employer TeleCity installed 48v as standard, for their telco customers.

All the Pro's (Cisco Juniper etc) offer 48v Kit as server makers targeting the carier grade market.

I have 48v in both my home rack, and the offices rack.