From an Outsell report, "Yahoo! recently unveiled a new feature on its image search page that allows a user to easily find pictures available for commercial re-use. After an initial search is conducted, a user simply selects the "More filters" link that appears below the search box and then checks the box marked "Creators allow reuse". With its ownership of Flickr, Yahoo! is tightly integrated to a massive collection of images. It was recently reported that over 3.6 billion images had been uploaded to that site alone. The filter works off of the Creative Commons license system, which provides a free set of tools for content creators to mark their works with a variety of conditions around reuse."
Yahoo's results, in my opinion, are much fore accurate than if you search Creative Commons licensed material using the Advanced Search Page with Google.