There’s only a video available at the moment, unless you want to sign up to one of their language combinations, but Duolingo‘s concept is very very interesting. Basically their set up turns translation of web segments into a language learning facility. It would seem that there are levels from beginner to expert to ease you along (Children: you should always couple reading and writing of foreign languages with spoken and aural practice!).
Interestingly there is a TED video featuring Luis von Ahn, one of the creators of CAPTCHA, about his work with Duolingo and his motivations. CAPTCHA is currently being used to help with OCR – OCR fails on old books with faded writing for instance, but CAPTCHA offers the opportunities for a distribute solution to this problem – by getting humans to decode the words. With CAPTCHAs on 350 000 sites, some as large as Twitter and FB, they are now digitising about 100 million words a day – about 2.5 million books per year – via CAPTCHA (well, reCAPTCHA to be 100% correct).
This is a fascinating project, I highly recommend the video if you are a translator and want to see a threat bigger than machine translation.