I work with environmental data, part of which includes global measurement of wind speed at the water surface. Now, I'm certainly not an expert on how the sensors work exactly, but as far as I have read, satellites bounce microwaves off the surface of the water, where the wind creates ripples - not the big waves, but the small ones, often less than a centimeter in height. The scatterometer then analyzes the height differences of the ripples (differences are in millimeters or less) and runs a model to figure out how fast and from which direction the wind is blowing.

Based on this I would not be surprised if something similar as described in the grandparent post is possible with the latest and greatest in spy satellites. I'm guessing it would only be used with extremely high-value targets though. There is some interesting information available via the NRO if you dig around a bit.