Wikipedia community votes 75% in favor of CC BY-SA:
"The Wikimedia Foundation (WMF) has proposed that the copyright licensing terms on the wikis operated by the WMF � including Wikipedia � be changed to include the Creative Commons Attribution-ShareAlike (CC-BY-SA) license in addition to the current GNU Free Documentation License (GFDL). This will affect all text and rich media (images, sound, video, etc.) currently licensed under �GFDL 1.2 or later versions�.
via CC blog