Infinity Storage Media has a hybrid disc with both Blu-ray and DVD 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]