Of the more than sixty papers presented at the Third International Conference on Hypermedia and Interactivity in Museums, those selected for this volume raised particularly profound issues about the implications of multimedia and computing technologies for the representation of knowledge of cultural heritage. Nothing about the proposition that museums should extend their potential audience by digitally 're-presenting' their holdings and the knowledge they possess about them is simple; not technologically, culturally, or intellectually. In this volume the authors reflect in extremely sophisticated, and technically demanding ways on these implications. In the process, I believe, they make fundamental contributions to the future of multimedia computing in museums.