Unobtrusive and multiple-sensor interfaces enable observation of natural human behavior in smart environments. Being able to detect, analyze and interpret this activity allows for the implementation of various applications, including real-time surveillance and real-time support in smart home and office environments. We focus on smart meeting environments, where nonverbal behavioral cues sometimes tell more about issues such as discussion participation, involvement and contribution, than information obtained from verbal contributions. An important aspect of this behavior is the interaction between meeting participants. We regard the special case where some of the participants are at physically different locations, which hinders natural interaction. We discuss how we can exploit the ability of a sensor-equipped environment to detect nonverbal interaction cues and use these to allow and improve natural interaction between collaborating participants at distributed locations. We focus on ...