Yup the US version is out. I caught an obvious grammar error on one of the screens so I think they rushed the US version out, not a big deal though. They tell the story through screen shots of MGS4 and text but it's not at all exciting to experience the story this way. I think I'll just skip the simple story bits since they just give you a small paragraph which says something simple like, "So Snake was called out into action."
I have to say that I'm pleasantly surprised by the gameplay though. The game itself is highly polished. Everything looks and sounds good. The gameplay is simple in nature, aim and shoot, but the polish behind it makes it very enjoyable. I really hope games like this do well so developers have more incentive to pursue a high quality game on the ipod touch/iphone.