Tomasz wrote:
It's legally impossible. Copyright assignment requires a real legal contract, and you can't make those with anonymous people, no way.
Have you taken any law classes? IANAL, but I have. Most contracts are informal but still binding - like when Jimbo assigned his own Wikipedia copyrights to the Foundation.
And also by using your logic we could not let Anons contribute at all since, under your reasoning, we could not bind them to the terms of our license.
Having an easy to find copyright policy and a one line sentence in the edit window "By clicking save you indicate that you agree to the copyright terms of this website" is more than enough.
Oh and newspapers, magazines and the equivalent online counterparts very routinely state that all letters to the editor or posts made to them by the public are their property.
-- Daniel Mayer (aka mav)