Word Lens is an augmented reality app which "instantly translates printed words from one language to another using the video camera on your iPhone". A lot of AR apps are really interesting but too slow and buggy to use for anything other than showing off in the pub. If Word Lens works as well as it appears to in this video then it is the exception to this rule. Just imagine being on holiday and having your iPhone translate signs and menus for you in real time!
you can get Word Lens from the App store.