Beyond Oil, the View from Hubbert's Peak, by Kenneth S. Deffeyes, looks at an often cited study by a renowned geophysicist, M. King Hubbert. In 1956 Hubbert predicted that U.S. oil production would peak in 1970. When that prediction was proved accurate, people began paying attention to Hubbert's studies. In 1969 Hubbert predicted that world oil production would peak in 2000.
In his book, Deffeyes suggests that the peak is occurring now (he says official USGS studies have placed the peak in 2036). The oil companies aren't saying much one way or the other. But for circumstantial evidence, Deffeyes points out that no new oil refineries have been built since 1970 and giant oil tankers are being retired without replacement. Perhaps the oil companies know more than they are letting on; they won't invest in refineries and ships they won't need.
These suggestions are quickly answered with accusations that the environmental restrictions of the EPA's have unnecessarily limited the construction of new refineries. Those restrictions are being relaxed now and construction of new refineries is being considered. The current refining and deliver system for gas is stretched so thin that unexpected catastrophes, such as Hurricane Katrina, can result in skyrocketing prices and lines of cars at gas stations.