Index: modules/system/system.install
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.install,v
retrieving revision 1.528
diff -u -p -r1.528 system.install
--- modules/system/system.install	30 Nov 2010 01:05:24 -0000	1.528
+++ modules/system/system.install	2 Dec 2010 03:12:14 -0000
@@ -2965,6 +2965,15 @@ function system_update_7068() {
 }
 
 /**
+ * Change D6 'site_offline' variable to 'maintenance_mode' in D7.
+ */
+function system_update_7069() {
+  // The site may be an upgrade from D6, or it may have started as a D7 site.
+  variable_set('maintenance_mode', variable_get('maintenance_mode', variable_get('site_offline', TRUE)));
+  variable_del('site_offline');
+}
+
+/**
  * @} End of "defgroup updates-6.x-to-7.x"
  * The next series of updates should start at 8000.
  */