I saw this interesting post this moring (courtesy of digg). It seems that a group (the majority of) Canadian ISPs have agreed to implement a "Clean Feed" type content filtering solution that would inspect and filter traffic coming to and from their customers. The objective of the Canadian project seems to to be completely legit; in that these ISPs are tyring to protect their customers from content that the government would otherwise find illegal. The target here as I read it is to filter kiddie porn and otehr such badness.
Things to look at to learn more about Clean Feeds include cybertip.ca , the Internet Watch Foundation in the UK, and the Censorware Project.
Technical note: This content filtering technology used to be something that could be enabled on a Firewall. I recently learned that security feature images on some routers now (or soon will) have similar capabilities.