We have a lot of material about design--I think this is one of the strengths of the book. We talk about incremental design, continuous design, reflective design, simple design, risk-driven architecture in an incremental environment, and of course test-driven development.
We also talk about incremental requirements, visions and release planning and how they relate to requirements, appropriate documentation practices, identifying and recruiting requirements experts, and how to create high-bandwidth requirements communication channels with collocation.
James Shore, coauthor of <a href="http://www.amazon.com/Art-Agile-Development-James-Shore/dp/0596527675" target="_blank" rel="nofollow">The Art of Agile Development</a>. Website and blog at <a href="http://www.jamesshore.com" target="_blank" rel="nofollow">http://www.jamesshore.com</A> .