I updated to 10.5.2 today and tried playing an HD DVD. It still didn't play, but we're a step closer. Instead of just mounting the disc on the desktop, it now detects it as an HD DVD and launches DVD Player. The player itself is unable to play the disc, but it proves that Apple is still working on it. I only have an HD drive, not a BR, so somebody with a BR DVD drive should give one of those a go too.