Wireless Sensor Networks are emerging as one of the most promising research directions, due to the possibility of sensing the physical world with a granularity unimaginable before. In this chapter, we address some of the major challenges related to the collection and elaboration of data sourcing from such networks of distributed devices. In particular, we describe the concepts of data storage, data retrieval and data processing. We discuss how such data management techniques will be able to sustain a novel class of data-intensive applications, which use the network as an interface to the physical world. Then, we identify some threats to the deployment of such networks on a large scale basis. In particular, we argue that even if appealing, the underlying composition of very large and heterogeneous wireless sensor networks poses enormous engineering challenges, calling for innovative design paradigms. Finally, we discuss an alternative solution, and the related data management mechanism, for the provisioning of sensor-based services in future pervasive environments.