According to http://www.latimes.com/business/la-fi-prop37-genetic-food-labeling-20121108,0,7519439.story :
"The measure fell victim to a media blitz bankrolled by $46 million in campaign contributions from big biotech companies, including Monsanto Co., grocery manufacturers and agricultural firms."
It's difficult to fight big buck biotech monies. The issue is not dead; the fight for GMO food labeling will surely continue.