As someone who works with various security software and appliances daily, I can honestly say that content filtering is DIFFICULT to implement and is usually easy to bypass. What is usually required for effective content management is an ongoing updated database of WWW content which needless to say is impossibly huge. So that OLPC with filtering will either have to phone home to the mothership often for filter updates or will be obsolete in terms of nrop blocking the minute it ships unfortunately... if you ban images on a whole on the other hand it will work (all formats) but what would be the point of that...