title: jQuery - How to detect if an item is currently outside of the viewport?
body: <p>I'm building a page that will be using ajax to update a main content area.  Users will be clicking on items from a left hand menu bar to update a div to the right with search results. </p>
  
  <p>I want to detect if a user has scrolled down so far causing the right-hand-side results div to moved outside the viewport -- but has does one detect that?</p>