The net is easy to censor
pietersz.co.uk
pietersz.co.uk
If the IWF refused or this becomes more common then people will start taking action. Dialup, VPN's, SSH tunneling, Proxies and alternate DNS providers are all in one form or another a soloution to this style of problem, but until the problem becomes bad enought people won't react.
If you want proof that people will react go look up how to access Hulu from out side the US.
Blocking DNS (apart from the ISP's own server), blocking known foreign proxies, etc.