Ahh, so that's what that does

img_auth.php

@@ -5,7 +5,9 @@
 # everyone to be able to access. Your server must support PATH_INFO, CGI-based configurations
 # generally don't. 
 
+# Valid web server entry point, enable includes
 define( "MEDIAWIKI", true );
+
 require_once( "./LocalSettings.php" );
 require_once( "includes/Setup.php" );
 

includes/DefaultSettings.php

@@ -1,5 +1,4 @@
 <?php
-if( defined( "MEDIAWIKI" ) ) {
 
 # $Id$
 # DO NOT EDIT THIS FILE!
@@ -9,6 +8,9 @@ if( defined( "MEDIAWIKI" ) ) {
 # like $wgScriptPath, you must also localize everything that
 # depends on it.
 
+# This is not a valid entry point, perform no further processing unless MEDIAWIKI is defined
+if( defined( "MEDIAWIKI" ) ) {
+
 $wgVersion			= '1.3.0+';
 
 $wgSitename         = 'MediaWiki'; # Please customize!

includes/Namespace.php

@@ -1,4 +1,6 @@
 <?php
+
+# This is not a valid entry point, perform no further processing unless MEDIAWIKI is defined
 if( defined( "MEDIAWIKI" ) ) {
 
 # This is a utility class with only static functions

includes/OutputPage.php

@@ -1,4 +1,6 @@
 <?php
+
+# This is not a valid entry point, perform no further processing unless MEDIAWIKI is defined
 if( defined( "MEDIAWIKI" ) ) {
 
 # See design.doc

includes/Setup.php

@@ -1,4 +1,6 @@
 <?php
+
+# This file is not a valid entry point, perform no further processing unless MEDIAWIKI is defined
 if( defined( "MEDIAWIKI" ) ) {
 
 # The main wiki script and things like database

includes/Skin.php

@@ -1,4 +1,6 @@
 <?php
+
+# This is not a valid entry point, perform no further processing unless MEDIAWIKI is defined
 if( defined( "MEDIAWIKI" ) ) {
 
 # See skin.doc

includes/SkinPHPTal.php

@@ -26,6 +26,8 @@
 # 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 # http://www.gnu.org/copyleft/gpl.html
 
+
+# This is not a valid entry point, perform no further processing unless MEDIAWIKI is defined
 if( defined( "MEDIAWIKI" ) ) {
 	require_once "GlobalFunctions.php";
 	global $IP;

index.php

@@ -10,7 +10,9 @@ if(!file_exists("LocalSettings.php")) {
 	die( "You'll have to <a href='config/index.php'>set the wiki up</a> first!" );
 }
 
+# Valid web server entry point, enable includes
 define( "MEDIAWIKI", true );
+
 require_once( "./includes/Defines.php" );
 require_once( "./LocalSettings.php" );
 require_once( "includes/Setup.php" );