What’s so great about Google’s ‘translation glasses’?

Google teased translation glasses at last week's Google I/O developer conference, holding out the promise that you can one day talk with someone speaking in a foreign language, and see the English translation in your glasses.Company execs demonstrated the glasses in a video; it showed not only “closed captioning” — real-time text spelling out in the same language what another person is saying — but also translation to and from English and Mandarin or Spanish, e