Index: wp-admin/users.php
===================================================================
--- wp-admin/users.php	(revision 3629)
+++ wp-admin/users.php	(working copy)
@@ -282,7 +282,7 @@
 <form action="" method="post" name="adduser" id="adduser">
   <table class="editform" width="100%" cellspacing="2" cellpadding="5">
     <tr>
-      <th scope="row" width="33%"><?php _e('Nickname') ?>
+      <th scope="row" width="33%"><?php _e('Username') ?>
       <input name="action" type="hidden" id="action" value="adduser" /></th>
       <td width="66%"><input name="user_login" type="text" id="user_login" value="<?php echo $new_user_login; ?>" /></td>
     </tr>