My favorite definition of “play” came from my days at Crayola, where after exhaustive research and expert opinion, we landed on: “It’s what kids do.” That’s how kids learn about the world around them.
Play provides a safe environment for experimentation and (*gasp*) failure. Games offer the ability to role-play or introduce healthy competition.
Jess McMullin and others (Luke Hohmann, Serious Games, LEGO, Pat Kane) are using games and play within product, software, service and even policy development. This article via boxesandarrows describes why we use games, core game principles, how to apply games, and how to sell design games to your organization or client. There’s also some good links and great commentary.