The ebuild create a menu entry using the file mozilla-firefox-1.5-unbranded.desktop which refers to 'Bon Echo'. I think firefox-3.0 unbranded should be called 'Minefield'
Created attachment 158407 [details, diff] s/Bon Echo/Minefield/ If adding a new .desktop file for firefox-3.0 is not wanted, this patch might do the job.
Fixed, thanks!