"By embedding electroluminescent materials into the pattern of the wallpaper and incorporating a light sensor, the wallpaper responds to the lighting requirement of a room, acting as a decorative element when a room is naturally bright, and as a wallpaper light when the space requires more light. With power supplied from a solar charged battery or standard electricity, it can also be manually controlled to increase or decrease luminosity."
Other good ideas in there: "The Activity Wallpaper, by Tobias Skog, explores how a place can get an electronic "memory" of how it is inhabited: how people move around, socialize, make noise or spend time there." (This is an oldish theme from the HCI literature, in which documents or objects or places record previous usage or interactions for later users to see. Nicely applied to wallpaper, though.)
And then there's "The Not-So-White Walls, by Dario Buzzini, is an interactive wallpaper that works like a display, giving you the possibility to change patterns and content as you wish. Resistors placed behind the paper surface make the color of the paper change according to your fantasy: you can dim lights, turn on home appliances, read email on the wall, view pictures taken with a camphone, etc." Yes, but can I watch a movie on it?