blocking the ip will not be enough, as there are millions of other p*rn website on the internet.
So the children or whoever it is, will just go to other sites.
the best solution is
OpenDNS | Providing A Safer And Faster Internet , try it out, i can't imagine any computer in a home with children without it.
What we need is a to build a consensus and push the schools to implement a solution like
OpenDNS | Providing A Safer And Faster Internet or a solution program like
Astaro Internet Security - Provider of Unified Threat Management Solutions Which Protect Against Hackers, Spyware, Phishing and Virus Attacks, Worms and Spam.