I just stumbled upon this video and was blown away!
I downloaded the app and had a play. It’s not perfect, but really gives us an insight of what is possible with augmented reality technology. The free version simply reverses the words on the screen, so you can see how it works. It costs AU$6 to make it support Spanish to English translation and another $6 to support English to Spanish. It seems to only work in portrait view, once you tip your phone sideways it struggles.
I’m looking forward to Japanese language support, once that is available I’m sure I will use it extensively!