title: Meaning of referer param fb_source=games_ego
body: <p>I see many people coming to my facebook game with HTTP referer that includes<br/>
  fb_source=games_ego</p>
  
  <p>Previously all options were at<br/>
  <a href="http://fbdevwiki.com/index.php?title=Ref&amp;cb=7347" rel="nofollow">http://fbdevwiki.com/index.php?title=Ref&amp;cb=7347</a><br/>
  but "games_ego" is something new.</p>
  
  <p>What could it mean?</p>