My case exactly. I need to implement a feature in a Wordpress theme. Found a GNU licensed plugin for Wordpress which does that. Am i allowed freely to copy and modify those code parts and incorporate them in new product i intend to sell - a theme? Am i obligated to refer to that plugin or its author for copyrights or it's just restricted to make profit on GNU based SW?
Edit: The license I am looking for answers into is here - http://www.gnu.org/licenses/gpl-2.0.html Sorry for the poor clarity of the question.