US President Barack Obama shakes hands with Facebook CEO Mark Zuckerberg during a town hall meeting April 20, 2011 at Facebook headquarters in Palo Alto, California. (AFP/Getty Images)
U.S. President Barack Obama (L) jokes with Facebook CEO Mark Zuckerberg (R) during a town hall style meeting at Facebook headquarters on April 20, 2011 in Palo Alto, California. The president used the opportunity to outline his views on the budget deficit ahead of a looming battle with congressional Republicans over fiscal matters. (Getty Images)
US President Barack Obama speaks as Facebook CEO Mark Zuckerberg (R) looks on during a town hall meeting April 20, 2011 at Facebook headquarters in Palo Alto, California. (AFP/Getty Images)
U.S. President Barack Obama (L) talks with Facebook CEO Mark Zuckerberg during a town hall style meeting at Facebook headquarters on April 20, 2011 in Palo Alto, California. The president used the opportunity to outline his views on the budget deficit ahead of a looming battle with congressional Republicans over fiscal matters. (Getty Images)
Facebook Chief Operating Officer Sheryl Sandberg introduces Facebook CEO Mark Zuckerberg at a town hall meeting with US President Barack Obama April 20, 2011 at Facebook headquarters in Palo Alto, California. (AFP/Getty Images)
U.S. President Barack Obama (L) talks with Facebook CEO Mark Zuckerberg (R) during a town hall style meeting at Facebook headquarters on April 20, 2011 in Palo Alto, California. The president used the opportunity to outline his views on the budget deficit ahead of a looming battle with congressional Republicans over fiscal matters. (Getty Images)
Facebook CEO Mark Zuckerberg arrives for a town hall meeting with US President Barack Obama April 20, 2011 at Facebook headquarters in Palo Alto, California. (AFP/Getty Images)
US President Barack Obama and Facebook CEO Mark Zuckerberg (R) take their seats after taking off their jackets during a town hall meeting April 20, 2011 at Facebook headquarters in Palo Alto, California. (AFP/Getty Images)
US President Barack Obama shakes hands with an attendee after a town hall meeting April 20, 2011 at Facebook headquarters in Palo Alto, California. (AFP/Getty Images)
People watch a television as US President Barack Obama speaks during a town hall style meeting at Facebook headquarters on April 20, 2011 in Palo Alto, California. The president used the opportunity to outline his views on the budget deficit ahead of a looming battle with congressional Republicans over fiscal matters. (Getty Images)