I think it all rests in permission of the copyright holder. If you look back at TSR when they ran D&D, they were extremely vicious in protecting thier product. Right to the point that they were unable to create thier website because it infringed on their own restrictions!! But when Wizards of the coast took over, they did a complete turnaround, and now anyone can use and display D&D products and characters freely as long as it is not in a way that defames WOtC, they consider it almost as free publicity, which in a way it is.