Can anyone state anything good factual about ethanol as a gasoline additive? The only thing I can think of is that it boosts measured octane (allowing fuel companies to use lower-octane fuel for the rest of their gasoline) though unlike real octane which makes fuel less volatile but provide more energy, ethanol makes it less volatile by providing less energy.
Ethanol would improve emissions in a car without a catalytic convertor, but those aren't exactly the most common breed these days (and since they're generally collectible, people who drive them generally don't want to destroy the engines by running ethanol through them). AFAIK, farm equiment is exempt from fuel-additive requirements, even though gasoline powered farm equipment without catalytic convertors is probably the place such fuels would provide the most environmental benefit. Oh well...
For some reason, the EPA requires oxygenates in gasoline, presumably to lower emissions. There seem to be two choices, ethanol and MTBE. MTBE delivers better engine performance and does a nice job in preventing smog, but has a nasty habit of getting into ground water. Whether that is from tank leaks or is a tailpipe emission, I don't know.
Ethanol is safer for the environment, but it's a lousy fuel. Farmers love it, because it drives up the price of corn.