Social networks have two faces. One trumpets a heartwarming message about making the world a better place by connecting people. The other has a gimlet-eyed focus on extracting value from the data of those people. Today Twitter flaunted its mercenary side. At an event for software developers in San Francisco, recently returned CEO Jack Dorsey introduced several new initiatives aimed at making money from data on Twitter users and their activity. Partners such as Target and Hilton chipped in with endorsements of the value of information juiced from people who use the social network…