"Similarly, the licensing terms of Jon Hicks’ familiar “fox around the globe” Firefox logo do not permit the logo’s use in versions of the browser built from a modified source code tree. For this reason, many “strictly free” Linux distributions, such as Ubuntu, omit the logo in favour of a more generic alternative. If they didn’t, the logo would effectively limit how they could make use of the open-source Firefox code."
Now I understand why in kubuntu the icon for Firefox is teh same as deer park builds.