Me, I don't see personal learning environments (PLEs) from a constructivist perspective, but a lot of people do, including Graham Attwell in this post. A Personal Learning Environment is developed from tools or artefacts. Vygotsky (1978) considered that all artefacts are culturally, historically and institutionally situated. 'In a sense, then, there is no way not to be socioculturally situated when carrying out an action. Conversely there is no tool that is adequate to all tasks, and there is no universally appropriate form of cultural mediation.'" Well, quite so, but they're also personally situated, and that marks a key line of demarcation between me and the (social) constructivists.