I was having trouble getting selenium (under jenkins) to run iceweasel (on debian squeeze). selenium was whining that /usr/bin/firefox was a script. Symlinking the xulrunner stub to /usr/bin/firefox-bin didn't work since it would whine about not finding application.ini.
Thanks to Tero Tilus on running selenium under debian lenny, I find that the solution is to add /usr/lib/iceweasel to jenkins' path. That way it finds firefox-bin plus all the other files that firefox-bin needs to start.