Firefox is indeed free software, but not in every sense of the word. It's an open source product, but the binaries that they ship contain proprietary plugins and artwork. I'm not too scandalized by this knowledge, but in case your ideological sensibilities are offended, know that you're not alone: IceWeasel is a version of Firefox from the GNU Project that omits all non-free-as-in-speech art and software. It also adds some privacy features including one that guards against "image bugs," i.e. empty images used for user-tracking. If you prefer the full-fledged Mozilla suite, the same site also distributes the Gnuzilla, which exhibits the same principles.

[Via Boing Boing]