Just at the moment that gaming has achieved broad cultural acceptance, and a recognition that well-designed games can actually teach both habits of thought as well as content, a new class of entertainment and social technology is emerging which threatens to spark a whole new world of controversy about its value. Virtual worlds — or metaverses — are free-form 3D social environments that look like games but, with the rather hefty exception of MMOGs, don’t quite “play” like games. This talk explores how the rule-less, goal-less, self-constructed nature of virtual worlds is the breeding ground for a whole new ecology of learning.