Appreciative Inquiry (AI) is the study and exploration of what gives life to human systems when they function at their best. XP is a good example of AI at work, as it encourages teams to emphasize technical skills that they are already good at and amplify them to a “dials to 11” setting of over achievement.
AI suggests that strengths, successes and hopes are transformational - that is believing in success breeds success. Agile is not just about process and practices, but a belief in achievement. This was the topic of the keynote speech at Agile Italy 2007 in Bologna. (the slides are available)