Check for right WordPress page template on save_post hook

wpse46583_save.php

<?php
/**
 * Plugin Name: Template Check
 * Plugin URI:  http://wordpress.stackexchange.com/questions/60451/check-for-page-template-on-save-post-hook/
 * Description: 
 * Author:      Frank Bültge
 * Author URI:  http://bueltge.de
 * License:     GPLv3
 */

add_action( 'save_post','wpse46583_save', 10, 2 );
function wpse46583_save( $post_id, $post ) {
	
	// verify this is not an auto save routine. 
	if ( defined('DOING_AUTOSAVE') && DOING_AUTOSAVE )
		return;

	// You should check nonces and permissions here
	if ( ! current_user_can( 'edit_page', $post_id ) )
		return;
	
	// only for debugging, get an list of all templates for pages
	var_dump( get_page_templates() );

	if ( esc_attr( $_REQUEST['page_template'] ) !== 'page-contact.php' ) {
		// No page template assigned - do something here.
		wp_die( 'wrong template' );
	}
	
	return;
}