Flickr removes all Obama Joker images to comply with takedown request. Who issued it?

Latimes blogs are buzzing: Flickr has removed the 'Obama Joker' image to comply with takedown request. Flickr groups are already calling it Epic Fail and have a discussion group collecting links and info on this. NYTimes asks: Censorship or Copyright Infringement?

On a site forum, Flickr, a Yahoo property, says it isn't banning accounts for posting the altered version of a Time magazine cover.
However, the company did receive a notice of infringement under the Digital Millennium Copyright Act, or DMCA, which sparked the removal, wrote Heather Champ, Flickr's director of community.
When asked who filed the request, Champ wrote in a follow-up e-mail, "We aren’t able to give that information out."
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"I don't know how this crazy game of telephone got started," Champ wrote. "I'm not sure how complying with the law has led to the idea that we (the Flickr team) have a particular political agenda."

Previous Obama-joker posts here.
Obama Joker Socialism Creator Revealed — And It Only Gets More Confusing
Obama as Joker posters - PR agency arranged coup or real street art movement?
Update : Przydzial filed the Flickr "Obama Joker" image takedown request. Because Przydzial originally made it