A content based messaging audio and video conferencing system provides a messaging infrastructure for multimedia and collaborative applications. The audio/video conferencing system may be implemented using a publish/subscribe infrastructure, such as a content-based messaging (CBM) infrastructure and system. Conference participants may exchange audio and/or video data streams using the CBM system. A list of contacts displays the current status of users. For example, the status of a user may be offline, online, and in a conference. The conference system uses the publish/subscribe infrastructure to provide instant state changes in the contact list using published updates to generate state messages for those users subscribing to contacts using the conference system.