case-shortcodes.php

<?php
/**
 * Plugin Name: Case Sensitive Shortcodes
 * Plugin URI: http://wordpress.stackexchange.com/q/102375/6035
 * Description: Are shortcodes case sensitive.
 * Author: Christopher Davis
 * Author URI: http://christopherdavis.me
 * License: GPL-2.0+
 *
 * Copyright 2013 Christopher Davis <http://christopherdavis.me>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2, as 
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * @category    WordPress
 * @author      Christopher Davis <http://christopherdavis.me>
 * @copyright   2013 Christopher Davis
 * @license     http://opensource.org/licenses/GPL-2.0 GPL-2.0+
 */

!defined('ABSPATH') && exit;

add_shortcode('sOme_ShOrTcOdE', 'wpse102375_shortcode');
function wpse102375_shortcode($args, $content=null)
{
    return 'yep';
}