Nodes behind the gateway have private, non-routable IP addresses and will appear to the public Internet using the IP address of the gateway.
If it is the wireless router that is "seen" as the IP address, who gets the responsibility for illegal actions, like downloading illegal music or pictures?
The point of contact for the connection, or in other words, if you are subscribing to a cable Internet or DSL and pay the bills, you are legally responsible.
And, with the recent RIAA insanity, it appears that the point of contact will be held liable for any illegalities that occur, regardless of whether he or she committed the act in question.
If I were to go to one of the usenet sites used by illegal porn distributors and dl a few gigs of images or go to a sharing site and collect a dozen or two complete CDs, I’d be safer using someone else’s connection and an external drive. If the feds happened to be tracing IP returns, it would show some poor guy who never encrypted his router.
After the feds came in and take his box and ALL of the digital media in his house (some bad guys put data discs in music CD cases, labels and all, so FBI takes them), and a search of his house thorough enough to find a 16K thumb drive, and make the usual comments like “You are in deep, deep trouble. Just cooperate and we’ll ask the judge for leniency. You know, having over 200 images can get you twenty-four months in Club Fed...”, when they finally let him loose in six months of hearings and interviews, he’ll encrypt his router when he gets it back.