Oil prices falling?

How would a drop in the price of oil affect the environment? It's not too hard to figure out- if oil is cheaper, people will tend to use more of it, emitting more greenhouse gases as they do so. The huge spike in gas prices in 2008 had people speculating that society was on the brink of a major shift to alternative fuels and to a national fleet with significantly higher gas mileage. Those things could still happen, but if prices are low there will be that much less incentive to get the job done soon.