Former U.S. Vice presidential candidate and Alaska Governor Sarah Palin (R) greets some of the thousands of motorcycle enthusiasts and military veterans participating in 'Rolling Thunder' rally May 29, 2011 in Arlington, Virginia. Although not an official guest, former U.S. Vice presidential candidate and Alaska governor Sarah Palin is expected to participate in today's motorcycle parade from the Pentagon to the National Mall.

Kazuo Hirai, President and Group CEO of Sony Computer Entertainment America, presents the Playstation Vita at the Sony Playstation media briefing on the eve of the Electronic Entertainment Expo (E3) on June 6, 2011 in Los Angeles, California. More than 45,000 people are expected to attend the annual three-day convention to see the latest games and announcements from the gaming industry. (Photo by David McNew/Getty Images)

In this handout image provided by the European Space Agency (ESA) and NASA, the International Space Station and the docked space shuttle Endeavour orbit Earth during Endeavour's final sortie on May 23, 2011 in Space. Italian astronaut Paolo Nespoli captured the first-ever images of an orbiter docked to the International Space Station from the viewpoint of a departing vessel as he returned to Earth in a Soyuz capsule. (Photo by Paolo Nespoli - ESA/NASA via Getty Images)

Artist Elizabeth Thompson poses next to her Blu-tack Spider sculpture at London Zoo on October 25, 2007 in London, England. The sculpture, known as “Blu-ey”, is a model of a common house spider and is completely made out of blu-tack. It is on show at BUGS! at ZSL London Zoo. The sculpture is made from around four thousand packets of Blu-tack and weighs over 200kg. (Photo by Chris Jackson/Getty Images)

Infantrymen of the US First Army shake hands with Russian soldiers on the broken bridge over the Elbe after the link-up at Torgau, Germany. The US soldiers are (L-R): Pfc. John A Metzger, Delbert E Philpott, and Pvt. Thomas B Summers; all are from A Company, 271st Regiment. (Photo by Allan Jackson/Getty Images). 04-1945

Participants enjoy mud during the 14th Annual Boryeong Mud Festival at Daecheon Beach on July 16, 2011 in Boryeong, South Korea. The mud, which is believed to have beneficial effects on the skin due to its mineral content, is sourced from mud flats near Boryeong and transported to the beach by truck. (Photo by Chung Sung-Jun/Getty Images)

The burning Polaris of Jose Antonio Blangino of Argentina sits in the sand dunes during stage one of the 2012 Dakar Rally from Mar Del Plata to Santa Rosa de la Pampa on January 1, 2012 in Santa Rosa de la Pampa, Argentina. (Photo by Bryn Lennon/Getty Images)

Duncan Fenton from the Society of William Wallace stands next to a 700-year-old letter believed to have been in the possession of William Wallace, which has returned to National Records of Scotland on January 12, 2012 in Edinburgh, Scotland. (Photo by Jeff J. Mitchell/Getty Images)