title: Make images load when they enter visible section of browser?
body: <p>I was browsing around the web and I saw something I've never seen before.
  on this site:
  <a href="http://blogof.francescomugnai.com/2009/04/mega-roundup-of-geektool-scripts-inspiration-gallery/" rel="noreferrer">http://blogof.francescomugnai.com/2009/04/mega-roundup-of-geektool-scripts-inspiration-gallery/</a></p>
  
  <p>When you navigate down the page, the images only load when they are in the visible portion of the browser.
  I have never seen this before and was wondering if anyone else has and how exactly one would do it.</p>
  
  <p>I'm guessing this is some sort of Wordpress plugin (that's what he's using) but I'm not sure.
  Is it javascript?  Are they actually loading on page load but just become visible later for a "snazzy" effect or is this actually useful for quicker page load times?</p>