Sensitivity and advertising

Ad agency DDB Brasil is facing outrage over an ad it created that used imagery evoking 9/11 to make a point about the tsunami and conservation for client World Wildlife Fund (this story is a touch confusing, so I recommend watching the ad posted at the end).
A print ad ran once in obscurity, and the agency initially claimed it hadn't created a video that was working its way around the Web. But when the blogosphere lit up, everything came out.
What is the role of sensitivity in advertising? Give me an example of a time a shocking ad might be used to positive effect. Do you think this ad should have been created and run? What cross-cultural issues are at play, given that the 9/11 attacks were against the U.S. but this agency is international?