During the last decade research groups as well as a number of commercial software developers have started to deploy embodied conversational characters in the user interface especially in those application areas where a close emulation of multimodal human-human communication is needed. Incarnations of such characters differ widely in type and amount of embodiment - starting from simplistic cartoon-style 2D representations of faces, fully embodied virtual humans in 3D virtual worlds to physically embodied androids co-habiting the user?s real world. Despite of their variety, most of these characters have one thing in common: In order to enter the user?s physical world, they need to be physical themselves. My talk focuses on challenges that arise when embedding synthetic conversational agents in the user?s physical world.