The problem is in English itself, like in the linked article, the "recognize speech" / "wreck a nice beach" examle. Without paying close attention to both the context of the conversation and the words itself it's only hardly distinguishable. The rules get even more relaxed around direct speech, popular phrases like "Beam me up" and jokes. The ambiguity that particular words / phrases can be written down in several different ways is the problem. In my native language (http://en.wikipedia.org/wiki/Czech_language), I'm not aware of any word/phrase that you could write down in different ways without changing its meaning (or just trying to look stupid). I guess there will be some cutting-edge AI programming and massive data processing behind first real speech recognizer (the one which works with all/most languages on earth), but who knows :)