5.1 Support is there. Apple sells the Logitech 5.1 speaker system on the Apple Store and mentions optical hookup. No way that happens without DD support in the OS.
well at first the pull down meny made me realize it was there. althogh it didnt say it why else would there be a pull down menu. so i went to help and typed in 5.1 adn walla, there it was. go check it out.
The only other new feature I can find is that you can make the info window and the closed captioning transparent (a user contollable amount). You can only do this on a Quartz Extreme enabled Mac. I can't post a shot of it as Grab will not take screen shots when a DVD is playing 🙁