Microsoft has come out and denied that the leaked images are real. In talking to the New York Times, a Microsoft spokesperson said, "The Daily story is based on inaccurate rumors and speculation." And, Microsoft also told ZDNet that the image is fake. Some would say that this would wrap up the story without trouble, but the thing is that just because the image is fake doesn't mean that Office for the iPad is fake.
Microsoft never specifically denied that Office for the iPad was in the works, which does mean a lot coming from the tech giant. So, we wouldn't be surprised if Office for the iPad made an official appearance soon enough.