This paper describes the implementation and use of a platform designed to support collaborative multimedia applications in a mobile environment. The platform provides a programming interface compatible with emerging open systems standards and includes services for processing multimedia information. In addition, the platform provides feedback to applications and users on the state of their communications infrastructure - an important requirement in mobile environments. The services provided by the platform have been used to develop a collaborative multimedia application designed to support a specific class of mobile worker, i.e. field engineers. The design decisions taken in our implementation of both platform and application are evaluated, and our experiences are presented.