Interactive spaces with multiple networked devices and interactive surfaces are an effective means to support multi-user collocated collaboration. In these spaces, surfaces like tablet PCs, tabletops, or display walls can be combined to allow users to interact naturally with their personal or shared information, e.g. during presentation, discussion, or annotation. However, designing and implementing such interactive spaces is a challenging task due to the lack of appropriate interaction abstractions and the shortcomings of current user interface toolkits. We believe that these challenges can be addressed by revisiting model-based design techniques for object-oriented user interfaces (OOUI). We discuss the potential of OOUIs for the design of interactive spaces and introduce our own object-oriented design and implementation approach. Furthermore we introduce the ZOIL (Zoomable Object-Oriented Information Landscape) paradigm that we have used as an experimental testbed. While our approach does not provide automated model-driven procedures to create user interfaces without human intervention, we illustrate how it provides efficient support throughout design and implementation. We conclude with the results from a case study in which we collected empirical data on the utility and ease of use of our approach.