We all know that computers are stupid. They can't tell the difference between "turning right" and "being right", or "this object is light" and "turn on the light". They just search for the word and if it appears, they show you where it is. They have no idea what it means. A better example is if I ask "who knows Ben Shoemate?" Google search can't tell me, even though I have friends in facebook, connections in linkedin, followers on twitter, comments on my blog, and links to my website...it has all the dots, it just can't connect them.
Once we teach computers how to understand the meaning of words in context, they can start to connect the dots and become a lot more useful to us.