$(function(){
   $('.thumb').css
   ({
   -moz-opacity:0.4; 
   opacity:0.4; 
   filter:alpha(opacity=40);
   })
   
   .hover(function(){
      $(this).animate
      ({
      -moz-opacity:1;
      opacity: 1; 
      filter:alpha(opacity=100);
      }, 'fast');
      
   },
   function(){
      $(this).animate
      ({
      -moz-opacity:0.4;
      opacity: 0.4; 
      filter:alpha(opacity=40);
      },'fast');
   });
});