We have had downward facing cameras on the B777 since 1998, considering that on approach we are doing over 200 mph, its extremely difficult to focus on anything that we fly over.
However, some of our playjets have cameras which can be zoomed in from 35000 ft, its amazing what you can see flying over the south of France.
Personally to avoid this intrusion on privacy, i suggest that all airliners be banned from flying during daylight hours.....
Mutt.