Firefox is getting even more of a leg up in a recent deal with Real Networks that will see the introduction of it and other free software included with RealPlayer. The deal, which is for the term of several years, will allow Real to bundle the option to install both Google Toolbar and Mozilla's Firefox when you install the program. While many have their complains about RealPlayer, it's definitely a plus over more “Free AOL!” icons or spyware you didn't ask for. They have plans to expand this as well:

The deal means that whenever users install RealPlayer, they will be given the option to also install either the Google Toolbar or Firefox. The distribution agreement will soon be extended to include downloads of Real's Rhapsody music service and RealArcade games. Real Networks said it "regularly distributes" more than 2m items of software a day worldwide.
Google was already in a deal with Real, and this is partly an extension of that. How or why Real benefits from this at a customer perspective is unknown, but likely a partnership of this nature can't hurt them.