I think the answer lies in even more information towards our user base. Users of Wikimedia projects, I think, just don't *get* the *free* part for most. It's just a cool thing they do, upload their pictures for Wikipedia...
Delphine
I'd suggest a questionnaire or a wizard-like sequence of questions and optional answers which results in suggestion of which license (if any!) best suits the author's will. I've seen something similar here: http://wiki.creativecommons.org/images/4/49/Choose_license_popup.png (accessible from here: http://wiki.creativecommons.org/Web_Integration_Guide)
For instance: * I declare I am the original author of the image. Y/N ** I allow commercial uses of my work. Y/N ** I allow modifications of my work. Y/N *** I require attribution. Y/N **** I require further distributions being released under the same conditions. Y/N
Good side is that people will make more informed decisions. Bad side... this will reduce the number of uploads...
Regards, Spritia