The veropedia project is finally up and running, and I'm very impressed with the results so far. After a quick browse of the site, I realized that what they are doing would likely be perfect for what I want to do with Wikijunior. It's a read-only website with prominent links back to Wikipedia (for editing). It also has a very simplified interface, which would be ideal for presenting to children.
One day, if the Wikijunior thing works out well, I would like to do something similar for ordinary wikibooks books. Stabilized versions of books would be an excellent tool for getting Wikibooks integrated into classrooms.