Chris and all a long winded answer that really isn't. I can't tell you for sure on the energy use, but I do know that two of the groups that are saying corn uses more energy appear to be backed by the oil industry. Check the wikipedia URL. One big concern is the government hoping for a 12M bushel corn crop which should meet the needs of most consuming groups. However, planting is behind schedule in several large areas of the corn belt due to weather. Here in the western area you want your corn in the ground by May 1 for best yield potential. There has been concern within the farm community about the impact of ethanol production on availability of corn for everything from critters to export to cosmetics. Many were hoping to use wheat for critter feed. There are wheat acres (froze out) being converted to beans, some corn ground that may go to milo or something else. Most raw food commodities wholesale prices are up in the last two years, but the cost is just now being passed on to the food consumer. Farm income is not up due to costs for gas, diesel, fertilizer. Fertilizer cost in Jan. is a good indicator of home heating cost the next winter or at least that is how we see in our home. I think of the long term thinking is corn ethanol is a stop gap measure. They want to use biomass. But no company has yet been able to produce ethanol from cellulose in mass quantities that can compete in price with corn ethanol. The whole international corn/wheat/soybean production v. demand for 2007/08 is a challenge due to demand and weather.
We use E-10 and biodiesel in our car, trucks, farm equipment. No real difference, but you may see a drop in mileage the first month. Our shop man says it cleans out the crud in the motor and then your mileage will return to normal. In winter you get a more visible tail-pipe emission with biodiesel, but my understanding it is not more of a pollutant.