jdMorgan - 8:20 pm on Feb 1, 2010 (gmt 0)
Bathroom scales and light fixtures can use non-routable private network (LAN) addresses, such a 192.168.0.x or 10.x.x.x and their status/commands can be routed using NAT, just as are most private-network (meaning yours) computers'. This allows them to share the single public-network address, e.g. the "WAN" address configured in your router.
Any use of public IP addresses for bathroom scales or light fixtures is due to lack of networking knowledge and abuse of the IP addressing scheme.
Not that I don't agree with ICANN, here -- Switching to IPv6 would give us back an awful lot of headroom to grow the internet.