The Context: Smart Cities can be viewed as complex systems aiming at improving the individual experience of the user/citizen using or interacting with city resources. These complex systems comprise a lot of communicating resources that dynamically associate and aggregate forming clusters of intelligent entities requesting/consuming or creating/providing/sharing valuable functions and data. These complex systems will be based on the integration of communication, storage, processing and sensing/acting capabilities provided by individual resources, terminals, smart objects and networks. These entities will be organized in stable clusters (associated to a government or business organization) or in a dynamic manner according to a casual aggregation of smart objects, users terminals and mesh networks. Data will be produced and consumed by resources in this highly dynamic context through different communication models. In addition data, resources and identities will be intertwined creating the needs: a) to sort out in real time the problem of ownership and anonimization of data, and b) to gather data for organizations (to determine the status, the behavior and the usage of the system) and for the single user (the Digital Footprint, i.e., the set of actions, data, interactions and outcomes with city related esources and networks). Users will leave behind in the smart environment a part of their digital footprint made out of data, actions and information that can be used to infer the past, present and future personal behavior. This personal footprint has to be protected and safeguarded from illegitimate usage and it should be preserved and returned (e.g., stored) to the user for further usage. The regulated usage and aggregation of personal footprints made available (under clear and fair rules and contracts) by the users could greatly contribute to increase the global intelligence of the whole smart environment. Being part of such a dynamic environment poses several challenges to communication providers: - How communication resources can adapt, support and organize in this context? - What services/functions could be provided for easing the communication between communication entities and how to dispatch the right event/data to the right resource/consumer? - How to create, protect and safeguard the User Digital Footprint? How to allow the usage and the aggregation of the Digital Footprints data increasing the number of applications, services and functions that the user can exploit? How to foster the integration of Digital Footprints of users creating a community able to share relevant data favoring the common wealth and knowledge? The speech will go through some scenarios and will discuss how selforganization of edge networks and resources, the application of Pub/Sub mechanisms in a sort of Twitter of Things platform, and the fair management and control of the Users' Digital Footprints could foster the creation of a smart city environment that directly exploit the power of "social data" and in which communication providers have the opportunity to play a prominent role.