Facebook CEO Mark Zuckerberg arrives at Japan's Prime Minister Yoshihiko Noda's official residence prior to a meeting with the Prime Minister in Tokyo on March 29, 2012. Facebook has more than 800 million users around the world and is the leading social network in all but six countries, notably Russia, where local rivals are preferred, and China, where it has been banned since 2009. AFP PHOTO/ POOL/ Yuriko Nakao