Will the real Bill Gates please Tweet? Microsoft's co-founder has  joined the ranks of microbloggers. 
  Gates' first tweet as @billgates: "'Hello World.' Hard at work on my  foundation letter -
publishing on 1/25." His last before retiring for  the night: "@aplusk thanks to you and all the other people who have  welcomed me. I've got a lot to learn about Twitter but look forward to  sharing
more." Gates racked up 107,361 followers within the first 8  hours. 
  Biz Stone, Twitter co-founder, welcomed Gates in a late afternoon  tweet. Ashton Kutcher became one of the first to welcome
Gates to  Twitter. Thousands of people followed with well wishes with tweets  streaming in a variety of languages from across the world. 
  Gates also rejoined social Facebook. He resigned from the
social  networking site about six months ago, after becoming inundated with  thousands of friend requests, according to reports. 
  Gates stepped down as Microsoft chief executive in mid-2008 to
spend  his time working with the Bill and Melinda gates foundation, an effort  devoted to better health and education. His Facebook page reflects his  philanthropic efforts and admiration for
technology.