"La Montagna di Sale (The Salt Mountain)" by Mimmo Paladino is displayed in Piazza Duomo on April 5, 2011 in Milan, Italy.

146 West End Stars hold a flashmob in support of the non-profit organistation Love 146, which campaigns to end child s*x slavery and exploitation, at Trafalgar Sqaure on April 11, 2011 in London, England. (Photo by Tim Whitby/Getty Images)

An employee demonstrates a Blackberry Playbook tablet at a Best Buy store on April 19, 2011 in Chicago, Illinois. The tablets, made by Research In Motion, went on sale today in the United States and Canada. (Photo by Scott Olson/Getty Images)

Castro's soldiers at Playa de Giron, Cuba, after thwarting the ill-fated US backed 'Bay of Pigs' invasion. (Photo by Graf/Getty Images). April, 1961

Musician Kirk Hammett of Metallica performs onstage during The Big 4 held at the Empire Polo Club on April 23, 2011 in Indio, California.

Opera singers perform in the pool “AquAria PALAOA” during a rehearsal at the swimming pool Neukoelln on April 27, 2011 in Berlin, Germany. The premiere of the underwater opera AquAria PALAOA is on May 1st. (Photo by Andreas Rentz/Getty Images)

A chimpanzee relaxes in the shade at the Safari Park as the popular attraction prepares for the upcoming Jewish festival of Pesach (Passover) on April 14, 2008 in Ramat Gan near Tel Aviv, Israel. (Photo by David Silverman/Getty Images)

Egyptian President Hosni Mubarak speaks to the media after talks with German Chancellor Angela Merkel at the Chancellery on April 23, 2008 in Berlin, Germany. (Photo by Sean Gallup/Getty Images)