However, some games that have DD 5.1 only have it for cutscenes - not in-game. Devil May Cry 3, MGS etc.
I've got one game that has DTS IN-GAME though! It's one of the EA NHL games (NHL 2002 I think) - Some other EA titles have DTS too real-time in-game, but they're not full 5.1, like SSX Tricky which is in DTS 4.0.
Still, it shows that it can be done in realtime which is one thing that people said the PS2 could never do - and there still aren't any exampled of DD5.1 used realtime in a game except for cutscenes.
More and more games are just sticking with DPLII for the most part, though - and this sounds great through a decent setup.
Black has possibly the best sound in any home videogame I've played, and it's "only" DPLII