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)

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)

The Facebook website is displayed on a laptop computer on May 9, 2011 in San Anselmo, California. An investigation by The Pew Research Center found that Facebook has become a player in the news industry as the popular social media site is driving an increasing amount of traffic to news web sites. (Photo Illustration by Justin Sullivan/Getty Images)

Actress Tang Wei poses at the “Wu Xia” portrait session during the 64th Annual Cannes Film Festival on May 15, 2011 in Cannes, France. (Photo by Andreas Rentz/Getty Images)

Crowds gather and watch the launch of NASA space shuttle Endeavour from Kennedy Space Center on the beach May 16, 2011 in Cocoa Beach, Florida. (Photo by Roberto Gonzalez/Getty Images)

Costume actors to wait before the show at “Chian Tourism Day” Inauguration Ceremony in Ninghai Zhejiang Province on May 19, 2011 in Ninghai, China. Various activities in local famous historic sites are being held to mark the day “China Tourism Day” on May 19. (Photo by Lintao Zhang/Getty Images)

Afghan security stands guard as a tractor eradicates a field of young poppy plants May 25, 2011, in Argu District, Badakshan, Afghanistan. (Photo by Paula Bronstein/Getty Images)