If you are considering invoking a Free Source effort, or converting to some sort of Free Source business model, it is important to first assess the motivations of the amorphous mass of intellect you hope to co-opt. No-one does something for nothing. Programmers will code for projects if it is relatively easy and not time-consuming to do so. Further, they will contribute a fix or modification if it in no way prejudices their efforts. Beyond that, motivation extends to personal gratification.
People respond to feedback and praise.
If the mechanisms exist for people's efforts to be appreciated, they are more likely to participate. Finally, there is the question of money. Free Source efforts can often have the beneficial side-effect of identifying quality talent for your enterprise. If a project centred around your enterprise or a product has already been created, identifying the champions of the effort can bootstrap you into an in-house adoption. The greatest mistake is to think that Free Source entitles you to a Free Lunch.