Ambassador Susan Rice hosts virtual town hall at Twitter

Twitter has about 200 million registered users around the world, with more than 60 percent of them international users. Though Twitter declined to say how many users are in Egypt, social media--including a service called "Speak2Tweet" -- has played a critical role in the Egyptian protests.

Katie Stanton, Twitter's vice president-international, fielded questions from Twitter users to Susan Rice, the US ambassador to the United Nations. The questions covered a wide range of topics, from UN peacekeeping in Darfur to the importance of investing in girls' education, concern about the Lord's Resistance Army in Uganda and Brazil's desire to become a permanent member of the UN Security Council. Ambassador Rice said that Twitter, Facebook and other forms of social media have had an "enormous impact on political movements, and governments are increasingly cognizant of their power." Ambassador Rice, whose Twitter username is @AmbassadorRice, has more than 12,000 followers. The US State Department recently launched a Twitter feed in Arabic to better communicate with the Arab world. "It's an extraordinary moment," Ambassador Rice said. "The power of this technology to channel and champion public sentiment has been more evident in the past few weeks."