The implications of this are, of course, rather worrying for home broadband users. There's nothing to stop your ISP from introducing a new clause to prevent you from operating Internet Connection Sharing on your own home LAN.
Their justifications will range from "better download speeds for normal, ungreedy users" to citing the increasing costs of technical support, however as always I am sure that its greed that motivates such things. "Want to connect a second home PC to the Internet? Why its so easy with the SECOND CABLE MODEM WE WILL RENT YOU!"
Its about time, I think, that broadband ISPs fully realise that we pay the extortionate amounts of monies involved to get cable, ADSL, etc, so that we can run NAT, P2P, etc and not have to worry about it! Get with the program, people. Stop conning us or we will find ISPs that treat us fairly.
And here, and here.