This article from Jan 13th deals with the possibilities of Biobutanol as a viable biofuel. Though biobutanol is not currently available enough to be competitive, the people that are developing it project that it could be competitive in four years.
Biobutanol is an interesting biofuel because, due to its higher density, it can be used not only as a basic transportation fuel but also as a jet fuel, can be made into plastic, and many other uses. It also yields a third more energy per gallon than ethanol. Since butanol is currently made from petroleum, it is not a great leap to see how being able to make it out of more sustainable sources is a good thing.
Another interesting thing about biobutanol is that since it doesn’t mix well with water, it can be pumped through existing oil pipelines without much changeover.