Studiodaily has this post this morning, but don’t get too excited its old news. It’s called a Hybrid Disc, and it’s been a possibility since High Definition Players were available. At one point playback was only supported on a G5, but then as HD DVD players began supporting burned discs, they functioned there as well and now subsequently with Blu-ray.

Basically you can make a short High Definition DVD and burn it to a standard DVD-R. This works because it functions based on format and file structure, the disc is just the storage medium - so in simplest terms, if the play back device supports the storage medium and you have the correct file structure you’ll get a functioning disc. Of course you’re limited to 4.7GB over the 25GB or even 50GB of Blu-ray, but you can do it. I think Jim may have actually written a tutorial on how to do this for HD DVD in the past - maybe we’ll swing something together for Blu-ray as well.