Index: wp-comments-post.php
===================================================================
--- wp-comments-post.php	(revision 6124)
+++ wp-comments-post.php	(working copy)
@@ -63,10 +63,18 @@
 $comment_id = wp_new_comment( $commentdata );
 
 $comment = get_comment($comment_id);
+
 if ( !$user->ID ) {
-	setcookie('comment_author_' . COOKIEHASH, $comment->comment_author, time() + 30000000, COOKIEPATH, COOKIE_DOMAIN);
-	setcookie('comment_author_email_' . COOKIEHASH, $comment->comment_author_email, time() + 30000000, COOKIEPATH, COOKIE_DOMAIN);
-	setcookie('comment_author_url_' . COOKIEHASH, clean_url($comment->comment_author_url), time() + 30000000, COOKIEPATH, COOKIE_DOMAIN);
+	$setcookie = apply_filters('comment_post_setcookie', TRUE);
+	if ( TRUE == $setcookie ) {
+		setcookie('comment_author_' . COOKIEHASH, $comment->comment_author, time() + 30000000, COOKIEPATH, COOKIE_DOMAIN);
+		setcookie('comment_author_email_' . COOKIEHASH, $comment->comment_author_email, time() + 30000000, COOKIEPATH, COOKIE_DOMAIN);
+		setcookie('comment_author_url_' . COOKIEHASH, clean_url($comment->comment_author_url), time() + 30000000, COOKIEPATH, COOKIE_DOMAIN);
+	} else {
+		setcookie('comment_author_' . COOKIEHASH, '', time() - 30000000, COOKIEPATH, COOKIE_DOMAIN);
+		setcookie('comment_author_email_' . COOKIEHASH, '', time() - 30000000, COOKIEPATH, COOKIE_DOMAIN);
+		setcookie('comment_author_url_' . COOKIEHASH, '', time() - 30000000, COOKIEPATH, COOKIE_DOMAIN);
+	}
 }
 
 $location = ( empty($_POST['redirect_to']) ? get_permalink($comment_post_ID) : $_POST['redirect_to'] ) . '#comment-' . $comment_id;