This talk discusses visualization in the mobility context from two points of view. First, mobile devices have become powerful enough to support advanced forms of visualization, but mobile visualizations need to be approached differently from traditional ones. Second, mobile devices are more and more capable of recording information about the behaviour of users on the move, and visualizing this information can be important in domains such as urban planning, geomarketing, emergency management, and others. The speaker discusses the different aspects of visualization design for mobile devices, and shows some research results concerning a tool for the visualization of mobile users' behaviours.