As computing and displays become more pervasive and wireless networks are increasing the connections between people and things, humans inhabit both digital and physical realities. In this paper we describe our prototype Mirror Worlds framework, which is designed to fuse these realities: Fusality. Our goal for Fusality is to support innovative research and exhibitions in presence and collaboration, sensors and smart buildings and mixed reality in applications from engineering to art. By fusing live sensor data from the building and its occupants with online 3D environments and participants, we demonstrate a firstprinciples approach to online multi-entity messaging communication. This demonstration shows how the variety of Mirror Worlds clients can be supported through the open Web architecture. These technologies enable new possibilities for collaboration as well as directions for interoperability. Finally, we layout out our research agenda for the framework and discuss its transformative applications.