jQuery(document).ready(function(){
        jQuery('#mailingListButton').hover(
            function(){ // Change the input image's source when we "roll on"
                jQuery(this).attr({ src : 'http://www.hiphounds.com/wp-content/themes/hiphounds/images/mailing-list-button-hover.png'});
            },
            function(){ // Change the input image's source back to the default on "roll off"
                jQuery(this).attr({ src : 'http://www.hiphounds.com/wp-content/themes/hiphounds/images/mailing-list-button.png'});             }
        );
    });