$(document).ready(function(){

    //Set opacity on each span to 0%
    $(".rollover").css({'opacity':'0'});

	$('.img_list a').hover(
		function() {
			$(this).find('.rollover').stop().fadeTo(500, 1);
		},
		function() {
			$(this).find('.rollover').stop().fadeTo(1500, 0);
		}
	)

});