Comment by SEJeff

I think it would be super interesting if they started offering IEEE 1588 v2 aka Precision Time Protocol, but it would be much harder to offer compared to ntp. What they're almost certainly doing here is just running a cable to the roof where they have a GPS antenna and then run it into their datacenters into a time appliance (less likely) or a GPS pci card in one of their servers (more likely) that they then send out to those who want access.