I've been trying to zip together what I know about free online collaborative projects (like free software) and commercial free culture projects (like the just-released "Sintel" from the Blender Foundation or "Sita Sings the Blues" from Nina Paley). It's easy to get lost in the logistics of such a production. One of the questions I'm bound to be asked is "How do I know I'm going to get paid?" Artists have a strong fear against being "exploited", though they're often less clear on exactly what that means. A little bit of examination, though, shows this may be a strength of the "Creator Endorsed" free culture approach to marketing a work -- it makes fair payment a matter of personal financial interest to the publisher, as I hope to explain here.
Free software can be viewed as sort of a public good — everyone can benefit from it. Instead of paying for complete applications, buyers may wish to only pay for specific program elements they want, which the software lacks. Therein lies an opportunity to make money on free software, instead of around it.