Designer Jean Louis Frechin showed off these "chronopictographic" digital photo frames at the recent International Milan furniture show. Called Wapix YJMM, the pair are connected by a short-range wireless link. Transient images are passed between the two displays, with the distance between each unit altering the speed at which it travels.
As illustrated in the first photo, the panels themselves are part digital photo frame and part light-box. A space between the translucent screen and the back-lighting system allows ambient light to affect image quality, in a way Frechin describes as "the quality of a digital ektachrome". Pictures are transferred to the displays via WiFi.
Proximity sensors make the image respond to movement, whether transitions or blurring, and the computer software uses simple widgets to build up slideshows. There's no indication of whether this will see a commercial release, but I'm sure it could be in-part replicated by a keen DIYer.