World's First Single-Sided Blu-ray/DVD Hybrid Disc Unveiled [Blu-Ray]
Gizmodo — ... data layers. This means that it'll play on your ancient budget DVD player but it'll also play in high-def in a Blu-ray player. This is done by stacking the DVD layers on top of Blu-ray layer with permeable layers of varying thickness in between. The differing wavelengths of blue and red lasers allow them to penetrate to a specific depth and read off the corresponding layer. Though the concept is far from new, Infinity is the first to bring these discs into production. [AV Watch] ...

Blu-ray / DVD hybrid discs to go on sale in Japan
Obsessable News Feed — The discs have gone into production in Japan, and they can be read by both Blu-ray and DVD players. There's no guarantee you'll be able to pick one up in North America or Europe anytime soon (or ever), but new discs that can store information readable by both DVD and Blu-ray players have gone into production. Infinity Storage media is the company responsible, and the details of how it was done are a little bit technical, but it suffices to say that the DVD data is stacked on top of the Blu-ray data, and the discs are constructed in such a way that the different kinds of optical readers present in DVD and Blu-ray players will only read the layers they're intended ...