A couple of questions that haven't been brought up yet but have recently passed through my mind:
1) Is it considered an acceptable use of resources to use koji to scratch-build private FOSS packages that will be hosted on fedorapeople.org?
2) What about pointing people to the builds hosted within koji?
3) What about building in koji but hosting elsewhere?
I think it's safe to assume that building anything non-FOSS in koji is *completely* out of the question.