[Twinny]

Another great feature of NAT: you don't know how many times you're connection runs through a nat box. Since the address effectively stops at the translation, you'll probably only be able to trace up to the ISP. Most ISPs have a very limited amount of ips to use.

Still..I want IPv6 already. With the amount of addresses it has available: NAT's won't be needed for IP address overloading. Though they could still be used for extra security.