Kevin,

Might as well reply to you, especially since my name was mentioned in your post. ;-)

People might like to read up a bit about IP addresses, proxies and NAT. A wireless NAT router in a Starbucks in NY might exhibit the same IP address for thousands of PCs in a 24-hour period. A large organization would typically attach a single or limited range of IP addresses to all their employees' outgoing browser and e-mail activity. Or they may put one PC with a non-company internet account in the lunch room for employee use during breaks. A business traveler using VPN from his Boston hotel could produce traffic that appears to originate in his Los Angeles office. So IMHO you'd need to subpoena logs from the ISP and router-managers before you can possibly match an IP address to a particular device, let alone a particular user. JMHO.

I originally said some other stuff but removed it at the request of somebody else, which seems to be becoming fashionable around here. ;-)