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. ;-)
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1