Nowadays pedagogy is inserted in a intense technological mutation of the media. Communication and technology are transforming our relationship with time and space, producing an accelerated rhythm of changes both in the world itself and in our knowledge of it. With the expansion of software and Internet resources, information and communications technologies (ICT) had opened way for a new relationship with knowledge, yet to be explored in the education and professional development of teachers. At the same time, in this context of transformations which affects both culture and teaching profession, such workers are faced with the task of constructing a new knowledge based on their actual pedagogical experience. Such knowledge must integrate the new scientific contributions to their practice. The present work discusses the professional development of teachers facing new information and communications technologies in public education. It is based: a) on the challenges that such technologies present to the pedagogical mediation; b) on the analysis of some educators on how informatics affect the formation of professors; and c) on discussions with mentors of professors of the Nucleus of Educational Technology of Rio de Janeiro (NET).