What do you think about the Associated Press vs. Shepard Fairey?

“The Associated Press has threatened to sue the artist who created the iconic “Hope” poster of Barack Obama for copyright infringement, but Shepard Fairey says his work is protected under the principle of “Fair Use,” which exempts artists and others from some copyright restrictions, under certain circumstances.
Pre-empting the suit, the Stanford Law School’s Fair Use Project filed a lawsuit on behalf of Fairey stating that his work is protected under Fair Use.”

For those unfamiliar, the poster was drawn from a photo that a freelance photographer had taken during a Darfur panel. The photographer was there to photograph George Clooney mainly, but snapped some of Obama as well.
This was the topic on Thursday’s “Fresh Air” on NPR and the text above is from that.

Ok, so what do you guys think? I’m wrestling with this one myself. Do we have the right to take another artist’s work and change it for a different intention or use? Is a quick photograph taken for the news not allowed to be used without permission for an “artistic” purpose? Would the AP care if Fairey’s poster didn’t make any money? What about Warhol’s Campbells soup paintings, etc?