According to a news published at Tech-On, Sony Sony Corp increased the surface recording density of coaxial holographic recording to 270 Gbits/inch². This is 1.5 times the density of the company's existing holographic recording technology, which is 180 Gbits/inch².

Some more detailed information about how this was achieved by Sony can be found here, but what makes interesting this news is how quickly holographic techniques are evolving. Who knows, maybe holographic discs will replace Blu-ray and HD DVD before these will be able to replace standard DVDs...