"This title sounds like a silly question. Open file formats serve everybody (except the monopolist), free software users and proprietary software users alike. Free software typically supports open file formats by default, and then maybe also some popular proprietary file format by necessity. Is there ever a situation where supporting/writing free software hurts open file format?
"Indeed there might just be one very interesting example: the docx plugin for firefox. I will leave the debate as to whether MS PL counts as a free software licnese to the lawyers (or philosophers). What I would like to point out is, whether this license is free enough, this particular piece of software is hurting us."
