Index: wp-includes/functions.php
===================================================================
--- wp-includes/functions.php	(revision 6668)
+++ wp-includes/functions.php	(working copy)
@@ -1676,4 +1676,18 @@
 			trigger_error( printf( __("%s is <strong>deprecated</strong> since version %s with no alternative available."), $file, $version ) );
 	}
 }
-?>
+
+/**
+ * wp_set_default_timezone() - Sets the default timezone to GMT.
+ *
+ * @since 2.5
+ *
+ * @return void Returns nothing
+ */
+function wp_set_default_timezone() {
+	if( function_exists('date_default_timezone_set') ) {
+		date_default_timezone_set('Etc/GMT');
+	}
+}
+
+?>
\ No newline at end of file
Index: wp-settings.php
===================================================================
--- wp-settings.php	(revision 6668)
+++ wp-settings.php	(working copy)
@@ -204,6 +204,8 @@
 if ( is_wp_error($prefix) )
 	wp_die('<strong>ERROR</strong>: <code>$table_prefix</code> in <code>wp-config.php</code> can only contain numbers, letters, and underscores.');
 
+wp_set_default_timezone();
+
 if ( file_exists(ABSPATH . 'wp-content/object-cache.php') )
 	require_once (ABSPATH . 'wp-content/object-cache.php');
 else