We present an interactive workspace that integrates wiki collaboration in knowledge-building activities with face-to-face scenarios like brainstorming or problem solving sessions. A wiki serves as the repository for knowledge elements, which are presented to co-located users in form of a concept map projected on a table. A computer vision module tracks multiple hands and fingers on the table surface and map elements can be manipulated using a simple gesture language. Also smart devices, like PDAs or tablets, can be connected to the system and participate in the interaction with their local input. The concept map and the wiki are synchronized in real-time, providing notifications to both co-located and distributed users and allowing a community shared awareness that enhances and enriches the knowledge building experience.