Yeah this is cool, I was so psyched when I first heard about it!
What's particularly cool is that their new song I.V is in the film
Saw IV in the credits scene. So everyone who likes X Japan has to go and see Saw IV to hear the awesomeness!
Also, although Hide is no longer with them, apparently a few of the guitar riffs in the song were actually written by him before he died (can anyone else confirm this?). So in a way it's like he climbed out his grave for this song... freaky, but again, cool.