[bparker]

Well its tricky as ARIN.net is the registrar for all internet IP addresses. Thus, when you register a block of IPs it will be registered that that orginization which may or may not be the actual address of the IP in question.

In most cases the IPs are owned by a company and the actual assigned IP is at that location OR assigned via VPN or DHCP Relay to a remote PC which is not at that location.

Arin.net are good lookups as it gives you a direct source to start working with but its not a 100% source.

Now some orgs have gone as far as revealing the assigned location by way of naming convention via DNS lookup which is what the GOV is calling for in all public networks but its not mandated.