grappler

<?php
// add ie conditional html5 shim to header
function _s_add_ie_html5_shim () {
    echo '<!--[if lt IE 9]>';
    echo '<script src="' . get_template_directory_uri() . '/js/html5.js"></script>';
    echo '<![endif]-->';
}
add_action('wp_head', '_s_add_ie_html5_shim');

makeusabrew

 $("form :input").each(function(index, elem) {
    var eId = $(elem).attr("id");
    var label = null;
    if (eId && (label = $(elem).parents("form").find("label[for="+eId+"]")).length == 1) {
        $(elem).attr("placeholder", $(label).html());
        $(label).remove();
    }
 });