diff -Naur drupal-6-3.orig/modules/comment/comment.module drupal/modules/comment/comment.module
--- drupal-6-3.orig/modules/comment/comment.module	2008-04-25 22:58:46.000000000 +0200
+++ drupal/modules/comment/comment.module	2008-08-04 15:38:41.000000000 +0200
@@ -753,8 +753,10 @@
           }
         }
 
-        $edit['timestamp'] = time();
-
+        if (empty($edit['timestamp'])) {
+	  $edit['timestamp'] = time();
+	}
+	
         if ($edit['uid'] === $user->uid) { // '===' because we want to modify anonymous users too
           $edit['name'] = $user->name;
         }