Rather than trying to explain what is an « Augmented Collaboration in Mixed Environments » (ACME) , I think this video sums up perfectly this concept. You can see a mixed reality teleconferencing application based on Second Life (SL).
Augmented Reality techniques are used for displaying virtual avatars of remote meeting participants in real physical spaces, while Augmented Virtuality, in form of video based gesture detection, enables capturing of human expressions to control avatars and to manipulate virtual objects in virtual worlds.
This application is developed by the VTT Technical Research Center of Finland