According the latest Annual report on Energy Generation in the USA they have reached a turning point:
In 2007, for the first time, renewable energy sources, other than conventional hydroelectric capacity, accounted for the largest portion of capacity additions. Total net summer capacity increased 8,673 MW in 2007. Wind capacity accounted for 5,186 MW of this new capacity. Natural gas-fired generation accounted for 4,582 MW. Two new coal-fired plants with summer capacity totaling 1,354 MW were placed in service in 2007. However, retirements and downward adjustments to existing capacity resulted in a 217 MW net reduction in coal-fired capacity.
