"The ethical commandments on the digital manipulation of photographs in journalism are simple and direct: you do not add or subtract any element of an image in post processing." - James Estrin
In a fascinating story on the NY Times blog, you can see the before and after photos which ultimately caused Narciso Contreras to lose his job with the Associated Press. The changes in exposure are subtle and were not the problem. It's the cloned corner in the bottom left that takes it too far. Read the entire piece here.