Dave Thomas, as one of the authors of the Agile Manifesto, understands agility. As the author of "Programming Ruby," he understands Ruby. And, as an active Rails developer, he knows Rails.
David Heinemeier Hansson is the creator of the Rails framework.
Clark is a consultant, author, speaker, and programmer. He helps teams build better software faster through his company, Clarkware Consulting, Inc.
James Duncan Davidson is a freelance author, software developer, and consultant focusing on Mac OS X, Java, XML, and open source technologies. He is the author of Learning Cocoa with Objective-C (published by O'Reilly & Associates) and is a frequent contributor to the O'Reilly Network online website as well as publisher of his own website, x180 (http://www.x180.net), where he keeps his popular weblog. Duncan was the creator of Apache Tomcat and Apache Ant and was instrumental in their donation to the Apache Software Foundation by Sun Microsystems . While working at Sun, he authored two versions of the Java Servlet API specification as well as the Java API for XML Processing. Duncan regularly presents at conferences all over the world on topics ranging from open source and collaborative development to programming Java more effectively. He didn't graduate with a Computer Science degree, but sees that as a benefit in helping explain how software works. His educational background is in Architecture (the bricks and mortar kind), the essence of which he applies to every software problem that finds him. He currently resides in San Francisco, California.
Justin Gehtland, a professional programmer, instructor, speaker and pundit since 1992, has developed real-world applications using VB, COM, .NET, Java, Perl and a slew of obscure technologies since relegated to the trash heap of history. His focus on "connected" applications led him to COM+, ASP/ASP.NET and JSP. Justin is the co-author of "Effective Visual Basic" and "Windows Forms Programming in Visual Basic .NET" (both Addison Wesley). He is currently the Agility columnist on The Server Side .NET, works as a consultant through his company Relevance, LLC, and teaches for DevelopMentor.