It's a combination of lots of things and it is global, not just here in the US. We just don't see much of what happens everywhere else because our news media doesn't show it.
I truly believe that the corn to ethanol has less to do with soaring prices than the value of the dollar, inflation, and fuel prices do. It's simple math. Everything we buy is transported, usually at least 3 times. From the manufacturer to a distributor to the retailer. Each move requires fuel, then if it's an import you have to add in shipping from their port to ours, plus all the other transportation. All of this takes fossil fuels to do it. That cost is passed on in the form of fuel surcharges and eventually the retailer builds it in to their final price. You figure one hell of a lot of freight gets moved for say, $.85 / mile. Fuel eats most of that up for a trucking company. Then you have the salary to the driver, usually anywhere from $.28 to $.42 cpm. With diesel now over $4.00 / gallon these companies are forced to try and raise their rates - something not substantually done since de-regulation in the 1970's. As they say - shit rolls down hill, so we - the consumers - end up being hit with the increases. It's nasty and painful, but I guess we'll live with it - we always have.