High resolution imagery of sub-meter – less than 40 inches – is only available from GeoEye, DigitalGlobe, Astrium Geo, and ImageSat. It is what the stuff of Google is made of. GeoEye and DigitalGlobe represent approximately 75% of this market, and 2/3 of their revenue is tied to the U.S. government. There are lots of free, government sources of satellite imagery like Landsat, and weather satellites from NASA and NOAA, but these are not high-resolution satellites that can zoom in on your house, or support 3D modeling for engineering and virtual reality-type applications.
Read about why U.S. commercial satellite imagery is important: