For exaqmple
> Think of it: my Facebook friends lists has EU and US people in it. This list can't reside in EU or US. This webpage can't be served by either a EU or US web-server.
This is plainly wrong, a reference tyo an user in a list is not the user data
A reference will not be enough when my friend wants to see my name and photo on the list. And if my friend must fetch it from Europe (and not cache it), expect Facebook to be slower and use more bandwidth than ever.
Without intercontinental replication, you'll be facing latency and bandwidth problems which will make social networks impossible.
note: when I say bandwidth, I mean intercontinental bandwidth, not your local internet bandwidth.