DESPITE MICROSOFT CORP.'S INVESTMENT IN social network Facebook, Bill Gates has been spending time hanging around with a different online social crowd. Two weeks ago, he posted his profile on the LinkedIn professional network. Gates has also reportedly shut down his Facebook page after being overwhelmed by thousands of friend requests. In addition to the LinkedIn profile, Gates posed a question on the site asking LinkedIn's more than 20 million users for advice on how to encourage more young people to pursue science and technology careers (www.linkedin.com/answers/technology/ information-technology/computers-software/TCH_ITS_CMP/179866-21879399). Maxing out its marketing coup, LinkedIn timed the posting of the question so that it coincided with its launch of a revamped home page design and the introduction of a new tool that enables members to broadcast their daily activities to their connections. Gates also purchased ads on the site.