One of the main reasons we showed off this demo -- even though we had real discs like Serenity and Phantom of the Opera to demo -- was that it included a "picture-in-picture" feature to show off HD DVD's ability to decode two video streams at once. At the time, none of the shipping titles included support for PiP, so we showed our concept demo for this feature.
But as of today, the real Bourne Supremacy disc is out, and it's the first title to include PiP support with an extended commentary / documentary track playing in time with the movie. There's a nice review over on High-Def DVD Digest, and as the author notes this is really just the tip of the iceberg. So next time we do a trade show, we'll be able to show a real disc with PiP rather than a "concept demo", which always seems kind of smoke-and-mirrors even though it's not.