Recent years have witnessed increasing interest of people in creating, sharing, collaborating and socializing in many other different ways among new open and decentralized social structures called Virtual Communities (VC). They represent entities aggregation with common interests, goals, practices or values. VCs are particularly complex, uncertain and risky environments wherein trust became, rapidly, a prerequisite for the decision-making process. Within such context traditional techniques of establishing trust are regularly challenged and new trust models should be proposed in order to raise these new challenging issues.