In order to make optimal educational use of social spaces offered by thousands of international communities in the second generation web applications termed Web 2 or Social Web, ICT competences as well as social skills are needed for both teachers and learners. The paper outlines differences in competence structures of Net Natives (who came of age in the 21st century) and the Net Generation of the 1980s and 1990s who evolve in response to changes between Web 1 and Web 2 technologies. Virtual educational environments in the age of the Social Web represent a perfect embodiment of the Constructionist paradigm: they offer shared discussion and work spaces instead of presentation tools, coaching utilities instead of help desks, and digital learning resource repositories instead of ready-made learning materials. LRE, the European Learning Resource Exchange, and several collaborative web based services and applications will be presented, to illustrate the interrelated change in educational software design and use. New teaching and learning aids require and at the same time inspire new educational theories. The trialogical learning paradigm that invites all educational stakeholders to work on shared objects of inquiry and development and thus develop epistemic agency will be offered as a foundation for a "social CALL".