Hours after the U.S. Geological Survey (USGS) released estimates that affirm the Deepwater Horizon spill in the Gulf of Mexico is the worst in U.S. maritime history, President Obama announced new limits on U.S. offshore drilling to allow for "further study and deeper reform."

Although most of the measures are temporary while a new commission studies the environmental risks and regulatory options of such drilling, industry observers have braced for profound change. (See "Oil Spill Poses Risk to Gulf Power Plants.")

Energy-industry analyst Kevin Book, for instance, sent a note to clients marking a turning point in what he characterized as two decades of pro-drilling sentiment from both the White House and Congress, spanning both political parties.

"A policy of