Add date shortcode with format and timestamp

// http://www.gravityhelp.com/forums/topic/user-notification-with-future-date
if ( !function_exists('date_shortcode') ) {
    function date_shortcode( $atts ) {
        extract( shortcode_atts( array(
            'format' => 'l jS \of F Y',
            'timestamp' => 'now'
        ), $atts ) );
        return date( $format, strtotime( $timestamp ) );
    }
    add_shortcode( 'date', 'date_shortcode' );
}