What are the rules for using data in Freebase?
It depends on what type of content it is. Data is available for use under the Creative Commons Attribution Only (or CC-BY) license. This means you are free to use it on your site, as long as you credit the Freebase community appropriately. The Freebase attribution policy has all the details. Many of the images in Freebase are also CC-BY, although some images are hosted under different license terms, like GFDL (which is similar to CC-BY), public domain, or Fair Use, and you can use the Freebase API to filter your results by license type. Finally, long descriptions that they have pulled in from Wikipedia are licensed under the GFDL.
