No, Google Earth sources its images from Google's own Streetview camera vehicles and from its public photography site, Panoramio. However, there is a green 'kml' button in the footer of every image page which allows you to see the particular image in Google Earth. Similarly, you can download the results of every search as a kml file for display in Google Earth (link near the bottom of the search results page). For an overview of all Geograph kml feeds, see http://www.geograph.org.uk/kml.php .
On the other hand, Geograph images are automatically transferred to Wikimedia, and many are already being used in Wikipedia pages in many languages.