Contractor Discounts When Working With Open Source?

mborland asks: "As I am contemplating doing contracting for a living, I have set my rates, and am allowing hiring organizations the option of a discount if certain portions of my work are released into the public domain under GPL. This at least benefits me, as I can feel free to easily reuse code for other projects; it arguably helps the organization, especially if the code is any good to begin with, and gets improved over time. If I do work for an organization which requires, for various reasons, that the code be propriety, then they pay full price--and they are happy to do so. But most places who just want something to work well and do not care about code ownership are happy to consider a price reduction. Any experiences with this? Thoughts?" This is an interesting way to professionally advocate the use of Open Source. What do you think about this practice, especially those of you working in the industry as contractors?