According to a few sites out there, it has been stated that there is no English track on the new Metal Gear game for the fact that it just couldn't be fit on to the Blu-Ray disk. So no subtitles or English voice track on the Japanese version. Which means that unless you can speak and read the language, you will have to wait for the game to come in your language instead of importing. Sounds bad at first, but that means that they used up the entire 50GB there has to be a really long game or a game that will blow everyone's minds.
Now you may be saying, what does this mean for us who don't want the game on PS3? That means that you most likely won't be seeing a port to any other system. Unless Microsoft retracts there statement of not going Blu-Ray. Or you'll be back to the good old Disc Swap of the Final Fantasy VII days. But that would be about 7 disks for the 360 version of the game. This is kind of why I liked Blu-Ray in the first place, the 50-100GB of storage on disk.