[thinkcomp]

Despite what some random developer says on a bug report, the Firefox logo artwork is actually governed by the Mozilla trademark policy.

http://www.mozilla.org/foundation/trademarks/policy.html

Furthermore, the implication that words are trademarks and logos are non-trademarkable works of art is misleading. Names and phrases registered as trademarks are called word marks, and graphical logos are considered design marks. Both are trademarks (or servicemarks if you're offering a service).

This is a pretty useless discussion in any event. If you're wondering how to protect your logo, you should really ask a lawyer. All I'm saying is that your lawyer will tell you that you should trademark your logo, and that copyrighting it would be a complete waste of your time.