I'm happy to see that people are proposing ways to make their choices without having to use the government to help them out. There is nothing worse than calling on the devil for help; ideally the government wouldn't be the devil but that is what it is to me now days. The idea of proposition 37 which would use government force to control markets is completely wrong and no liberty minded individual should be promoting such an activity. Remember that no one is forcing you to purchase GMO products, it is your choice and your choice only. There are already laws that forbid false advertisement, so if a company adds Organic to their label, I think (not positive) that it includes the meaning of being non-GMO.
Another great market solution to this problem, and anyone feel free to start this company up, would be to have an independent company test or verify that foods are non-GMO. If this company is ever incorrect, it will tarnish their image and open up the market for other companies. So this would keep the influence of companies such as Monsanto from putting pressure on them. Something to think about.