English
• Possibly my favorite site is Big Learning - Photography for Kids. Not only can you find projects and articles for the aspiring young photographer, but also the history of photography and how cameras work.
• 13 Lessons to Teach Your Child About Digital Photography - Love it!
• Kodak has a page of lesson plans on photography.
• Artists Helping Children has a huge list of photography crafts for kids.
Books
• The Kids' Guide to Digital Photography: How to Shoot, Save, Play with & Print Your Digital Photos by Jenni Bidner
• Photography for Kids!: A Fun Guide to Digital Photography by Michael Ebert and Sandra Abend
• 4-H Guide to Digital Photography by Daniel Johnson
Spanish
• XatakaFoto has a couple of good articles in Spanish: Fotografía para niños - Parte 1 and Fotografía para niños - Parte 2.
• HP also has a really great web page in Spanish on how to introduce your child to digital photography - Cómo iniciar a tus hijos en la fotografía digital.