With OPEC declining to limit oil production last week, an abundance of oil on the market has driven prices down to roughly $70 per barrel, and an average of $2.77 per gallon of gasoline. Steve Benen has a good summary of the politics behind the numbers (and how Republicans were willfully wrong about the President's energy policy that imposed fuel efficiency standards, etc.). Lower oil prices are a boon for the American consumer, who will have increased discretionary income, but bad news for Putin's Russia, which exports a significant volume of oil and is struggling with economic sanctions and a flat economy. It also effects the economics of tar sands and oil shale from Canada and North Dakota, reducing pressure for building the Keystone XL pipeline, if extracting that oil becomes more costly than keeping it in the ground.
