Index: wp-includes/pluggable-functions.php
===================================================================
--- wp-includes/pluggable-functions.php	(revision 3501)
+++ wp-includes/pluggable-functions.php	(working copy)
@@ -287,6 +287,7 @@
 	setcookie(PASS_COOKIE, ' ', time() - 31536000, COOKIEPATH, COOKIE_DOMAIN);
 	setcookie(USER_COOKIE, ' ', time() - 31536000, SITECOOKIEPATH, COOKIE_DOMAIN);
 	setcookie(PASS_COOKIE, ' ', time() - 31536000, SITECOOKIEPATH, COOKIE_DOMAIN);
+	setcookie('wp-postpass_' . COOKIEHASH, ' ', time() - 31536000, COOKIEPATH);
 }
 endif;
 
Index: wp-includes/template-functions-post.php
===================================================================
--- wp-includes/template-functions-post.php	(revision 3501)
+++ wp-includes/template-functions-post.php	(working copy)
@@ -70,6 +70,10 @@
 			$output = get_the_password_form();
 			return $output;
 		}
+		if ( stripslashes($_COOKIE['wp-postpass_'.COOKIEHASH]) == $post->post_password ) {	// and it does match the cookie
+			$site = get_settings('siteurl');
+			$output = '<br /><a href="' . $site .'/wp-login.php?action=logout">Delete post password cookie!</a><br /><br />';
+		}
 	}
 
 	if ( $more_file != '' )