This paper was improved by conversations with a large number of people who helped debug it. Particular thanks to Jeff Dutky <dutky@wam.umd.edu>, who suggested the ``debugging is parallelizable'' formulation, and helped developed the analysis that proceeds from it. Also to Nancy Lebovitz <nancyl@universe.digex.net> for her suggestion that I emulate Weinberg by quoting Kropotkin. Perceptive criticisms also came from Joan Eslinger <wombat@kilimanjaro.engr.sgi.com> and Marty Franz <marty@net-link.net> of the General Technics list. Paul Eggert <eggert@twinsun.com> noticed the conflict between GPL and the bazaar model. I'm grateful to the members of PLUG, the Philadelphia Linux User's group, for providing the first test audience for the first public version of this paper. Finally, Linus Torvalds's comments were helpful and his early endorsement very encouraging.