In this paper we present a Mixed Reality (MR) teleconferencing application based on Second Life (SL) and the OpenSim virtual world. Augmented Reality (AR) techniques are used for displaying virtual avatars of remote meeting participants in real physical spaces, while Augmented Virtuality (AV), in form of video based gesture detection, enables capturing of human expressions to control avatars and to manipulate virtual objects in virtual worlds. The use of Second Life for creating a shared augmented space to represent different physical locations allows us to incorporate the application into existing infrastructure. The application is implemented using open source Second Life viewer, ARToolKit and OpenCV libraries.