The price of corn has risen so sharply due to the demand to produce ethanol, that it is not longer cost effective to produce ethanol as a replacement for gasoline. Plans to build new ethanol plants are on hold, and two plants under construction have filed for bankruptcy. Even with the price of gasoline on the rise, it is now more expensive to produce a gallon of ethanol than a gallon of gas, just as it was in the days when gas was 'cheap'.
However, the rise in the price of corn has a multifaceted effect, since when gas rises, the price of anything else rises to a small degree. When the price of corn goes up, the price of anything made with corn also rises to a greater degree, since all producers of any goods using corn have to pay the same price.
Also, GreenPeace is now saying the ethanol is no less polluting than gasoline, but then again, what did we expect from them?