It is hard enough to explain what we are doing to our professors; explaining it in plain English to our friends and family is nearly impossible.
So it is always good to see people who can explain what POS tagger is and why it is important without having to throw around references to Norvig or Jurafsky.
Markus Dickinson has managed to do exactly such explanation in his non-linguistic primer to a serious research paper on Detecting Errors in Part-of-Speech Annotation. The writing is quite old (2003), but it reads well and still feels relevant. Of course, his research page contains more recent papers on the same topic too.