That was quick. From the AP:

NEW YORK (AP) – Mayor Michael Bloomberg is backing off his suggestion to put windmills on city bridges and rooftops after newspapers mocked the idea with photo illustrations of turbines on the Brooklyn Bridge and the Empire State Building. “There are aesthetic considerations,” Bloomberg said. “No. 2, I have absolutely no idea whether that makes any sense from a scientific, from a practical point of view.” Bloomberg sought to dial back his windmill proposal while speaking to reporters on Wednesday after returning from Las Vegas, where he gave a speech at the National Clean Energy Summit imagining, among other things, harnessing wind power with turbines on bridges and skyscrapers. In the coverage that followed, one newspaper ran a front-page image of a turbine twisting on the Empire State Building’s iconic spire, while another showed what the Brooklyn Bridge might look like with three turbines planted high above it. David Carr, of the Alternative Energy Institute, in Canyon, Texas, said mounting turbines high above the city is “not very feasible.” “I don’t think this was very well thought out,” he said.