The main subject of this dissertation is captology, an area of study that comprehends the overlap of computer technology and persuasion. The research proposes a comparison between earlier suggested and the current development trends of persuasive technology. The study begins with a contextualization addressing the relation between society and computer technologies. It approaches the interaction design, with focus on the user, analyzing design approaches for the area with emphasis, at first, in user centered design, and then in experience design. In addition, the realm of ubiquity is presented as an important factor, when it comes to social/cultural, technological and usage views, concerning persuasive technology. A captology concept is then presented, with the ethical issues involved in designing with persuasion and the trends for the area, pointed by B.J. Fogg, one of the pioneers in the study of computers as persuasive agents. Focusing these trends, the research scope is delimited, defining iPhone fitness applications as core objects for the study. The dissertation presents the research, from the browsing and selecting process of applications, as well as interviews with developers, questionnaires with users and predictive evaluation of selected applications, to finally elaborate a comparative analysis between the pointed trends and the achieved results in the present moment, which reflect captology s state of the art.