These times, when the amount of information exponentially grows on the Internet, when most people can be connected at all times with powerful personal devices, we need to enhance, adapt, and simplify access to information and communication with other people. The vision of ambient intelligence which is a relevant response to this need brings many challenges in different areas such as context-awareness, adaptive human-system interaction, privacy enforcement, and social communications. The authors believe that ontologies and other semantic technologies can help meeting most of these challenges in a unified manner, as they are a bridge between meaningful (but fuzzy by nature) human knowledge and digital information systems. In this chapter, the authors will depict their vision of “Social Ambient Intelligence” based on the review of several uses of semantic technologies for context management, adaptive human-system interaction, privacy enforcement and social communications. Based on identified benefits and lacks, and on their experience, they will propose several research leads towards the realization of this vision.