IP address is not accurate enough to reliably ascertain such a thing. First, there's the problem of NAT. Second, there's the problem of dynamic IPs. My IP addre

IP address is not accurate enough to reliably ascertain such a thing. First, there's the problem of NAT. Second, there's the problem of dynamic IPs. My IP address changes everytime my modem is switched back off and switched back on. I'm sure a lot of other facebook users don't have static IPs as well. Point I'm making: This data is important to them and they're recording it. They have an easy and reliable way to access this data through persistent cookies which they've - ahem - left on user clients by mistake. A lawyer would call that circumstantial evidence. Of course, I can't be fully sure of my accusation. Hence the question mark.