Zooming around Northern California on Google Earth reveals that Google have extremely high resolution imagery for not just cities but also rural and wilderness areas. I would guess it's something around ~10cm, which must be from aerial imagery not satellites, right? If you'd like see what I mean search for "Big Bar, CA" in Google Maps or Google Earth and fly around a bit. What's more, it seems to be collected annually (at least for the last two years).
I have no idea how much of the country has this high resolution coverage, I've only just noticed it in my neck of the woods. And I'm specifically interested in the Northern California imagery.
Does anyone know the source of this data? Or is there a way to find the source? Google Earth lacks the familiar copyright notices at the highest resolutions and I'm stumped about how to proceed beyond that. I might be interested in purchasing the data if I could find the source.