Kim Cameron has some interesting discussion of the software here and here.

The following is a quotation from one of his posts:
There is no doubt that government has a legitimate interest in the safety of the Internet, and in the safety of our children.  But neither goal can be achieved with any of the unfortunate methods being used here.

Rather than so-called “blacklisting”, the alternative is to construct virtual networks that are dramatically safer for children than the Internet as a whole.  As such virtual networks emerge, technology can be created allowing parents to limit the access of their young children to those networks.

It’s a big job to build such ”green zones”.  But government is the strong force that could serve as a catalyst in bringing this about.   The key would be to organize virtual districts and environments that would be fun and safe for children, so children want to play in them.

This kind of virtual world doesn’t require the generalized banning of sites or ideas or prurient thoughts - or require government to “improve” the nature of human beings.