Only in privatemsg_inbox: CVS
diff -urp privatemsg_inbox/privatemsg.module privatemsg_count/privatemsg.module
--- privatemsg.module	2009-03-17 20:31:42.615955000 +0000
+++ privatemsg.module	2009-03-17 21:22:59.104555000 +0000
@@ -266,7 +266,7 @@ function private_message_settings() {
     '#options' => array(
       'participants'    => t('participants'),
       'thread_started'  => t('Started'),
-      'count'           => t('Answers'),
+      'count'           => t('Replies'),
     ),
     '#default_value' => variable_get('privatemsg_display_fields', array('participants')),
   );
@@ -694,7 +694,7 @@ function privatemsg_sql_list(&$fragments
   $fragments['select'][]      = 'pmi.thread_id';
   $fragments['select'][]      = 'MIN(pm.subject) as subject';
   $fragments['select'][]      = 'MAX(pm.timestamp) as last_updated';
-  $fragments['select'][]      = 'MAX(pmi.is_new) as is_new';
+  $fragments['select'][]      = 'SUM(pmi.is_new) as is_new';
   
   if (in_array('count', $fields)) {
     $fragments['select'][]      = 'COUNT(pmi.thread_id) as count';
diff -urp privatemsg_inbox/privatemsg.theme.inc privatemsg_count/privatemsg.theme.inc
--- privatemsg.theme.inc	2009-03-17 20:59:07.768355000 +0000
+++ privatemsg.theme.inc	2009-03-17 21:19:37.833155000 +0000
@@ -30,6 +30,11 @@ function phptemplate_privatemsg_list_fie
 function phptemplate_privatemsg_list_field__count($thread) {
   $field = array();
   $field['data'] =$thread['count'] -1;
+  $options = array();
+  if (!empty($thread['is_new'])) {
+    $options['fragment'] = 'new';
+    $field['data'] .= '<br />'. l((format_plural($thread['is_new'], '(1 new)', '(@count new)')),'messages/view/'. $thread['thread_id'], $options);
+  }
   $field['class'] = 'privatemsg-list-count';
   return $field;
 }
@@ -64,7 +69,7 @@ function phptemplate_privatemsg_list_hea
 
 function phptemplate_privatemsg_list_header__count() {
   return array(
-    'data'    => t('Answers'),
+    'data'    => t('Replies'),
     'key'     => 'count',
     'class'   => 'privatemsg-header-count',
     '#weight' => -25,