In this chapter, we consider the requirements for middleware to support Pervasive Information Systems (PIS) in the context of the Internet of Things (IoT). With the IoT, PIS architectures become more and more distributed and need to be supported by middleware that provides applications with an easy integration of contextual data collected from connected objects spread over the Internet. This comes with new challenges and requirements for PIS middleware. In addition to context-awareness, middleware should tackle scalability, security, privacy and interoperability and provide applications with new abstractions representing the physical environment and ensuring the quality of the data that may be used for decision-making, while keeping PIS sustainable. Through the study of the state of the art regarding PIS middleware, we show in this chapter that the middleware community still faces new challenges, such as providing high-level programming models for PIS, supporting PIS dynamic adaptation, disseminating and filtering large volumes of data, end-to-end privacy and interoperability handling, as well as enabling to deploy sustainable applications.