[WordPress] Dynamic copyright date depending on when the first post was published.

dynamic_copyright.php

<?php 
/**
 * Dynamic copyright date.
 *
 * Dynamic copyright date depending on 
 * when the first post was published on your site. 
 * 
 * Derived from: http://alex.leonard.ie/2010/07/27/wordpress-tip-get-the-date-of-your-first-post/
 * 
 */
function gp1305_dynamic_copyright_date() {

    $args = array(
    	'numberposts' => -1,
		'post_status' => 'publish',
		'order'       => 'ASC'
	);

	$posts = get_posts( $args );
	$first = $posts[0];
	$date = date( 'Y', strtotime( $first->post_date ) );

	return ( intval( $date ) < date( 'Y' ) ) ? intval( $date ) . '-' . date( 'Y' ) : date( 'Y' );
}