LinkedIn, a Web site that professionals use to make contacts and trade tips, created quite a stir this week. It announced that it raised $53 million in funding, primarily from Bain Capital Ventures, implicitly valuing the four-year-old company at an impressive $1 billion. It was only the latest evidence that social networks for the more-serious set -- think Facebook, as opposed to a more youth-oriented MySpace -- have come into vogue with investors. - FaceySpacey
