Echoing wmf, there's a bit of pro-GPL bias here.<p><i>"I'd rather my software was used in a hundred proprietary projects than by a dozen people who are truly free to use it." -- Then you are interested in popularity, not freedom.</i><p>It's all about whose freedom you want to preserve, not popularity contests. Copyleft licenses ensure the freedom of software recipients. Permissive licenses ensure the freedom of software developers.