Creative Commons Images in Google Image Search
According to the Google Operating System (unofficial Google blog), Google will add an option to limit images searches to those with Creative Commons licenses. In other words, you will be able to search for images that are legally acceptable to copy & use. There are other options as well, such as for commercial use and modifying the image.
In case you are curious, which you should be, the Creative Commons is a legal agreement & a list of flexible licenses that allow content creators to share their works with the world.
To test the upcoming feature or to read more, visit http://googlesystem.blogspot.com/2009/06/find-creative-commons-images-in-google.html