Turtles, Termites, and Traffic Jams: Explorations in massively parallel microworlds ISBN 0262680939 by Mitchel Resnick
Excellent book about decentralization and emergent behavior. There is a tendency in [humans|western society|whatever] to think in terms of complex patterns and behaviors as being the result of design or control. The book explores the many ways that complex behavior can arise spontaneously (or be designed to arise, too) from simple rules. Luckily he doesn't just talk about CellularAutomata, but about real world topics like termites and traffic jams, too.
A story from the book... Resnick asked a class of kids how they might design an army of robots to collect moon samples. Even though he'd been teaching them about emergent behavior and decentralization, and even though the problem he posed was identical to one he'd already shown them solved with emergent behavior (the termites), the kids still proposed schemes that had a "central control robot" directing other robots. So apparently this pattern of thinking is hard to overcome.
He thinks it is very important that we open our children to that way of thinking. I agree. It has changed the way I think... -- ToddCoram
See also StarLogo for the software described in the book.
What really made me buy this book was the acknowledgement's first sentence: