In the current quest for personalized and omnipresent healthcare required to address contemporary challenges, the typical concept of information systems interoperability is no longer expressive enough to address the complex interrelationships of the increasingly diversified technical environment in which the clinical processes occur. The traditional view of the healthcare information systems architecture considered only clinical information systems and healthcare facilities; however, as the Internet-of-Things vision becomes a reality, an exploding number of mobile devices, sensors, tags and other identifiable resources with communication and processing capabilities need to be added to the big picture. In such complex circumstances, the concept of interoperability also needs to evolve from the original concept of interoperating sets of information systems to the capability of each autonomous information system to sense, interpret, understand and act upon arbitrary messages received from potentially unknown senders. Therefore, in this paper we propose an evolved concept of interoperability as a property of a system, more suitable for the modern context of ubiquitous healthcare information systems. We define enabling factors for interoperable information systems involved in pervasive healthcare and we also attempt to assess and exemplify the impact that a novel Interoperability as a Property (IaaP) paradigm would have on the healthcare information systems’ landscape.