The field 'address' doesn't appear in the list of the potential hidden fields (setting 'hiddenuserfields'). Why?
However it is usually the main personal information to hide from other non-authorized users (other than course teachers/admins) for increasing student privacy.

Here is a obvious patch, tested with 1.8.2:
— MOODLE_0709/admin/settings/users.php 2007-03-28 18:57:05.000000000 +0200
+++ MOODLE_0706/admin/settings/users.php 2007-10-31 11:01:54.000000000 +0100
@@ -82,6 +82,7 @@
get_string('confighiddenuserfields', 'admin'), array(),
array('none' => get_string('none'),
'description' => get_string('description'),
+ 'address' => get_string('address'),
'city' => get_string('city'),
'country' => get_string('country'),
'webpage' => get_string('webpage'),