--- ../../../all/modules/formfilter/formfilter.module   2008-11-19 15:23:24.000000000 -0500
+++ formfilter.module   2009-02-03 12:25:31.000000000 -0500
@@ -244,6 +244,10 @@
       $value = isset($element['#default_value']) ? $element['#default_value'] : 0;
       break;
     case 'checkbox':
+      // If default_value is not empty (as a checkbox, that means checked) we return the return value.  Otherwise, 0 for unchecked.
+      $element['#type'] = 'hidden';
+      $element['#value'] = !empty($element['#default_value']) ? $element['#return_value'] : 0;
+      return;
     case 'radio':
       // TBD: Why doesn't passing values work for checkbox elements?
       //$value = isset($element['#default_value']) ? $element['#default_value'] : $element['#return_value'];