Thanks to ICT, new organizational forms are emerging that keep the pace of an increasingly demanding competitive environment. Among them, Virtual Enterprises (VEs) and Virtual Teams (VTs) represent two challenging organizational forms from the point of view of effective management. An open issue in VEs/VTs is the social and economical sustainability of knowledge sharing in virtual environments, which is often underestimated. We address it from the point of view of "virtual worlds" and developed a prototypal solution that facilitates the cooperative building/sharing of knowledge representation.