K9 is a content filtering service. They have expressed interest doing a linux version but it seems to be low on their priorities.
Their reply to a petition on their [forums http://forums.bluecoat.com/viewtopic.php?t=3179&postdays=0&postorder=asc&start=0] was... " We are currently working on K9 for Mac OSX. Afterwards, we will be working towards K9 for Vista 64bit. Linux is still a bit down the list.
We prioritize based on the number of users on each platform (weighted by the ease of developing for that platform). We would love to have a linux version - and, if all goes as planned, we will have one some day in the future.
Part of the difficulty is that K9 has a driver-level component...which means we would have to develop different versions of K9 for different distributions.
If you are interested in K9 for linux, rather than posting your reply "K9 for linux", please post what distro you would like us to target. That way, we can know where the interest lies - and can start the investigation process for that distro. "
I think with a little help from the community we could give them the little shove they need.
The service they provide is free(as in gratis) but is superior to most content filters out there. They get their blacklist from providing internet filtering for large corporations so it is extensive, They provide a slick web interface for remote managing, and there is no noticeable slowdown for the internet it filters.
They have provided filters for many school systems and it would be an appropriate application to add to edubuntu.