Facebook has a status update: The social network will open a new office in Cambridge next year and plans to hire more than 500 employees, bringing the Boston-based staff to 650. From a report: The company, which founder Mark Zuckerberg launched at Harvard before decamping for the West Coast, established its first Boston-based team nearly four years ago with a small group of employees sharing a workspace. Today, that team has grown to more than 100 people in a Kendall Square office, and space is getting tight, said Ryan Mack, who leads the Facebook Boston office. "We serve 2 billion people on Facebook," he said, "and we need to continue to scale." The new offices will occupy the top three floors of 100 Binney St., a new building designed by Elkus Manfredi that is scheduled to open early next year. Facebook will share the space with 300 Bristol-Myers Squibb employees.