Yes, aperture synthesis is possible with optical wavelengths. I don't know how practical it would be to actually use with spy satellites, or how much of an improvement they could see with it.
Keep in mind that there are a lot of people that track satellites, even spy satellites, as a hobby. I haven't heard of anyone discovering two or more satellites orbiting in the sort of tight formation you would expect would be required for this.
Keep in mind that there are a lot of people that track satellites, even spy satellites, as a hobby. I haven't heard of anyone discovering two or more satellites orbiting in the sort of tight formation you would expect would be required for this.