For those interested in familiarizing themselves with the structual principles associated with Complex Adaptive Systems, a good high level overview may currently be found at:

Complex Systems
and
Complex Adaptive Systems

along with the research referenced via these articles.

In addition, the following, by no means an exhaustive list, provides an alternative perspective:

The general reader.

• Linked: Albert-Laszlo
• small world: Mark Buchanon

Both provide a good introduction to the importance of network topology, and specifically how the nature of connectivity between a number of components directly affects the overall dynamics of the composite structure. Both cover the same subject material from different, but equally interesting perspectives. The historical review of graph theory in Linked is I found of particular interest.

• Critical Mass: How One Things Leads to Another : Philip Ball

An excellent introduction to group behavior and emergent properties from the perspectives of social science and physics!

• Creation: Life and How to Make It : Steve Grand

A must read for those wanting to understand the nature of virtualisation, AI and how to achieve self-learning/adaptive systems.

• Investigations : Stuart A. Kauffman

What principles drive structure and complexity? Investigates is a fascinating attempt at answering such questions, predominetly from a biological perspective.

For the specialist.

• Hidden Order: How Adaptation Builds Complexity : John H. Holland, Heather Mimnaugh
• The Complexity of Cooperation : Agent-based Models of Competition and Collaboration (Princeton Studies in Complexity) Robert Axelrod
• Swarm Intelligence : Eric Bonabeau, Marco Dorigo, Guy Theraulaz
• The Origins of Order: Self Organization and Selection in Evolution : Stuart A. Kauffman