You might be interested in look at projects like http://schools-wikipedia.org/ and other "subset wikis". When I worked at One Laptop per Child we distributed a offline Wikipedia slice along with the XO-1 laptops to many schools and children. We were in fact careful to curate our offline article/image slice to avoid gratuitously inappropriate content. We felt this to be an appropriate thing for OLPC to do, for its audience, *not* something we expected upstream Wikipedia to do. There are many differences between a "Children's Encyclopedia" and Britannica! OLPC did not censor links in any way, so a laptop connected to the internet could see and follow links to any article/image on Wikipedia (not just articles/images in our curated offline subset). Often schools deployed their own content-filtering firewalls on their network connections. We felt this was a matter best implemented and managed by the school, with their own local community standards.

Erik and I were spitballing wiki ideas last week, and one of the things we discussed was ways to make it easier for third parties to curate wikipedia subsets, as OLPC and the schools project did. It is certainly already possible, but it could be made easier. If you are interested in making a "child friendly wikipedia", that is certainly one way to go at it, and the ground is well trod. --scott