Looks like the wind farm has rendered on potlatch.

The proposed tag: power=generator; power_source=wind doesn't have any effect yet

http://wiki.openstreetmap.org/index.php/Proposed_features/Power_plants

Using man_made=power_wind works on mapnik

Neither are shown on osmarender layer - this would be quite useful, as you could see them without waiting a week for mapnik

I think the location might be this one?

http://xahlee.org/Whirlwheel_dir/livermore.html