I'll stay organic for the most part, don't like the idea of messing with foods even more than we already have.
Aside from that, the argument that GM could help feed thousands of starving people in poorer nations is good, but the biggest factor is subsidies/trade agreements and just plain wastage. If you don't tackle those issues, GM will just be another money making machine for Western (subbed) farmers who have plenty to live by already... 
and no offence to americans, but it seems you can make a direct correlation between the vast overproduction by US farmers and big portions in meals, and indeed growing waistlines. (edit - haha, and britains too after reading a few articles
especially children!)
Food doesn't need to be produced more efficiently, it needs to be sold at fair prices and to the right people.
[addsig]