Successful collaboration depends on effective communication. Ongoing group awareness facilitates communication by enabling workers to be more informed about their collaborators, about their activities, and about the interpersonal dependencies among people working together. In this paper we present MyUnity, a new system that aids workers in building group awareness. The system uses multiple sources, both automatic and user-provided, to report colleagues' location, availability, current tasks, and preferred communication channels. Information is aggregated, fused and presented as a simple presence state for each worker. Workers can each independently control what information is collected by the system, allowing them to participate in the system without compromising their privacy. Results from a four-week field study show MyUnity increased group awareness and fostered an increased sense of community in the workplace. Results provide insights into the utility of awareness systems in the workplace.