Customizing the Genesis HTML5 Comment areas to put labels inside entry fields and have them automatically clear when curser selects the fields.

clear_form_fields.js

jQuery(document).ready(function() {
	jQuery.fn.cleardefault = function() {
	return this.focus(function() {
		if( this.value == this.defaultValue ) {
			this.value = "";
		}
	}).blur(function() {
		if( !this.value.length ) {
			this.value = this.defaultValue;
		}
	});
};
jQuery(".clearit input, .clearit textarea").cleardefault();
});

functions.php

<?php
// Don't copy opening php tag

// Add support for clearing form default values
add_action( 'get_header', 'wsm_add_form_clear_script' );
function sc_add_gform_scripts() {
    wsm_add_form_clear_script( 'inputfileds', CHILD_URL . '/lib/js/clear_form_fields.js', array( 'jquery' ), '1.0', TRUE );
}

/* Note: You're going to want to add CSS to hide the comment form labels too, like this:
 * 
 * .comment-respond .clearit label {
 * 	display: none;
 * }
 * 
 */

// Set the Comment Form Defaults
add_filter( 'comment_form_defaults', 'wsm_comment_form_defaults' );
function wsm_comment_form_defaults( $fields ) {
	
    $fields['comment_notes_before'] = ''; //Removes Email Privacy Notice
    $fields['title_reply'] = __( 'Share Your Comments & Feedback:', 'wsm' ); //Changes The Form Headline
    $fields['comment_field'] = '<p class="clearit comment-form-comment"><label for="comment">' . _x( 'Comment', 'noun' ) . '</label> <textarea id="comment" name="comment" cols="45" rows="8" aria-required="true" tabindex="4">' . __( 'Comment', 'wsm' ) . '</textarea></p>'; // Adds clearit class and default value to comment text area
    $fields['label_submit'] = __( 'Share My Comment', 'wsm' ); //Changes The Submit Button Text
    $fields['comment_notes_after'] = ''; //Removes Form Allowed Tags Box
    
    return $fields;
    
}

// Set the Comment Form fields
add_filter( 'comment_form_default_fields', 'wsm_comment_form_fields' );
function wsm_comment_form_fields( $fields ) {
	
	global $commenter, $req, $aria_req, $html5;
	
	$fields   =  array(
		'author' => '<p class="clearit comment-form-author">' . '<label for="author">' . __( 'Name', 'wsm' ) . ( $req ? ' <span class="required">*</span>' : '' ) . '</label> ' .
		            '<input id="author" name="author" type="text" value="' . __( 'Name', 'wsm' ) . '" size="30"' . $aria_req . ' tabindex="1" /></p>',
		'email'  => '<p class="clearit comment-form-email"><label for="email">' . __( 'Email', 'wsm' ) . ( $req ? ' <span class="required">*</span>' : '' ) . '</label> ' .
		            '<input id="email" name="email" ' . ( $html5 ? 'type="email"' : 'type="text"' ) . ' value="' . __( 'Email', 'wsm' ) . '" size="30"' . $aria_req . ' tabindex="2" /></p>',
		'url'    => '<p class="clearit comment-form-url"><label for="url">' . __( 'Website', 'wsm' ) . '</label> ' .
		            '<input id="url" name="url" ' . ( $html5 ? 'type="url"' : 'type="text"' ) . ' value="' . __( 'Website', 'wsm' ) . '" size="30" tabindex="3" /></p>',
	);
	
	return $fields;
	
}