I don't think I could ever say anything as well as Cory Doctorow, as demonstrated by his spot-on (and engagingly written) editorial on Internet filtering (aka censorware) that appeared in the Guardian today:
[Censorware] firms are profiteers, waxing rich on the fears of the free world and the oppression of totalitarian states. They operate without transparency and without accountability, and hide behind the excuse that they only supply ratings, leaving firms and ISPs to do the dirty work of choosing which ratings to block - "we only load the pistol and aim it, it's the mayor/your boss/a librarian who pulled the trigger".