How is this "carbon-neutral"? True, the amount of carbon released by the combustion is eventually sequestered by later crops of corn, but don't make the classic error of neglecting to factor in the carbon released from the supplemental processes (farm equipment, alcohol processing, transportation, etc.).
And while we're on the subject of ethanol, let's remain sober to the fact it is no panacea and requires more energy to produce than what can be derived from it.