One of the most well known examples of appropriation in recent times is the red, white, and blue Obama poster that says ‘HOPE’ on the bottom, designed by Shepard Fairey.
He took a photograph and appropriated it into this poster. Pretty soon after it caught on, other artists appropriated his work as well, as shown in the wikipedia page, displaying characters such as Anonymous and Gil Fulbright.
A lawsuit was held over the picture, which revolved around Fair Use. The AP claimed that the poster did not constitute fair use. Actually, what Fairey did did not constitute fair use, however the original artist, Manny Garcia, did not forgive Fairey, but he voiced his opinion that this poster did constitute fair use. Overall, Fairey and the AP agreed to a settlement and to work together going forward with the Hope image.