Informal communication is an essential resource in hospital work; it is used as a means to collaborate and coordinate the way in which work is performed, as well as to locate and gather the artifacts and human resources required for patient care. The need of physical proximity to establish and hold informal communications has motivated the development of tools that support remote informal interaction. However, this kind of technology has not been widely adopted in hospitals, where workers experience intense mobility. In this paper, we present the results of an observational study in a hospital aimed at understanding how local mobility changes the rules in the provision of support for informal communication, and how technology could improve this form of communication. We found that local mobility fosters opportunities for colocated communication; however, it faces some inconveniences related to the affordances of the physical environment. We address these issues through the design of SOLAR, a collaborative application that supports colocated interactions in hospital work through the implementation and integration of five services that form a ubicomp infrastructure. Additionally, we present a discussion about the perception of users related to the usefulness of this tool.