I have found information about pens that allow students learn a second language. These are called translating pens and they work this way: you scan a single word or full line of printed text and the pen translates or defines single words. You can also see and hear the scanned word(s) read aloud. Moreover, they are multilingual and alternative input tools are also included for entering words that you can’t scan (e.g., street signs).
I think they are going to be very useful not only for students of a second language but also for travellers and maybe for translators. However, I imagine they are not well developed still because as we saw machine translators aren’t and present a lot of problems (most of them dealing with the context surrounding the words). Moreover, as the video I posted about Microsoft Speech “Recognition” showed, these Text-to-Speech technologies also present some problems. So, I think these pens are going to be also problematic in both areas.
They look like this: