Almost every adult in the world can speak and comprehend speech, but most of us have no understanding of or appreciation for quite how amazing and complex this capability is. I'm not a linguist, but I've studied a lot of linguistics as part of my AI research and I'm constantly impressed by how intractable the problem is. Some people have made completely incredible and impossible claims regarding computers and language, but for the most part we really have no idea how the human brain does what it does.
Much of the difficulty in language stems from the need to disambiguate words and phrases that can have multiple meanings. Human language is incredibly redundant; there are a hundred ways to say the same thing, and any given word or sentence can have a hundred different meanings. Our brains learn (over the course of years, but still at a startling rate) how to perform these tasks, but we're still not able to teach (program) our computers to do the same things. (And I doubt we ever will be.)
Neal Whitman, who apparently is a linguist, presents an excellent example of just how confusing language can be. AI is a long way from being able to learn/generate/comprehend this type of result (other than with a rule-based approach, which is impractical), and we need more than an accumulation of baby steps to get there -- we need some dramatic breakthroughs that will radically change the way we think about natural language processing, because I think we're on an entirely wrong track.