Collaborative geographic information systems (GIS) are maturing into an important collection of tools, theories, and practices to directly support multi-stakeholder participation in the planning and management of geographically distributed resources. Collaborative GIS are situated in the broader disciplinary area of Group Spatial Decision Support Systems (GSDSS) and can be defined as an integration of spatially enabled theories, tools, and technologies for structuring human participation and articulating issues of concern in local and distributed spatial planning processes (Balram and Dragicevic, 2006). A typical system designwill include a digital workspace for map-based analysis and visualization, multi-modal interfaces for participant interactions, and digital databases to provide baseline data and store new information. In addition, the Collaborative GIS is usually integrated in a supporting organizational and technical structure to ensure continuity especially if change detection is a desired outcome. Spatial decision support and visualization have been two key application areas for Collaborative GIS designs. In their capacity as enabling platforms for spatial decision support, Collaborative GIS have served a variety of roles such as integrating virtual team participants (MacEachren, 2001), structuring planning processes (Balram and Dragicevic, 2005; Jankowski and Nyerges, 2001), balancing consensus and conflicts (Feick and Hall, 2002), and facilitating local stakeholder participation in resource decision processes (Nyerges et al., 2006). As a means to aid visualization for co-located or dispersed individuals and groups, Collaborative GIS have been used mainly to communicate planning scenarios and outcomes (MacEachren et al., 2005).