> Come on, let's be real. In grade school we learned that light goes around the earth 8 times a second. That means 1/16 of a second (63ms) to go around to the other side of the world. That doesn't set a useful lower bound since this is the ballpark of latency within a country anyway. You're just going to ping between the two servers and measure the latency.

So there's some funny folklore regarding this...

http://www.ibiblio.org/harris/500milemail.html