"Holographic projection screens"
Mia pointed out the holographic projection screens produced by http://www.holopro.com
HoloProTM enables projection onto glass in daylight while maintaining transparency. This is made possible by the patented HoloProTM technology: holographic optical elements are beamed onto a highly transparent film by laser. This is then embedded in glass. The light- guiding effect enables rear projection onto the glass screen. The result is a sharp, high-contrast picteven in broad daylight. HoloProTM screens become a component of the light and room concept. Individual sizes and shapes create lively information areas that structure the room without disturbing its transparency and effect. The transparency of the projection surfaces will lead to creative ways of presenting information. Interactive elements with touch or gesture control extend the possible areas of use.
(Theun) I came across this article about Hologpaphs that change: http://drawn.ca/2008/02/06/holographs-that-change/