Well, it's happened.

Up until a couple of weeks ago, we here in corn country (where many of the ethanol refineries are located) were enjoying ethanol at 10 cents per gallon cheaper than regular. Now that California and some of the NE states are have abandoned MTBE and are requiring ethanol, the price of ethanol here is suddenly 10 cents per gallon more than regular. I guess 33 million people (or so) in one state can have an impact on supply and demand...