Index: captcha.module
===================================================================
RCS file: /cvs/drupal-contrib/contributions/modules/captcha/captcha.module,v
retrieving revision 1.103.2.11
diff -u -b -u -p -r1.103.2.11 captcha.module
--- captcha.module	20 Oct 2010 19:35:06 -0000	1.103.2.11
+++ captcha.module	30 Oct 2010 20:55:53 -0000
@@ -390,6 +390,12 @@ function captcha_form_alter(&$form, $for
 
     }
   }
+  // Add a warning about caching on the Perfomance settings page.
+  if ($form_id == 'system_performance_settings') {
+    $form['page_cache']['cache']['#description'] .= '<p><strong class="error">'
+      . t('Warning: the CAPTCHA module will disable the caching of pages that contain a CAPTCHA.')
+      . '</strong></p>';
+  }
 }
 
 /**