Facebook has been working on a private beta of Facebook at Work for a while now. It is a way for corporations to have a private social network that's built on the back of Facebook. The service has now been officially launched with the name Workplace.
Facebook at Work is a division of Facebook that helps businesses communicate and share files in a private service.
They have just announced a dedicated chat application for Facebook at Work that is called Work Chat to help employees communicate even faster than before.