Index: includes/install.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/install.inc,v
retrieving revision 1.56.2.4
diff -u -p -r1.56.2.4 install.inc
--- includes/install.inc	16 Feb 2009 10:25:02 -0000	1.56.2.4
+++ includes/install.inc	9 Mar 2010 15:10:23 -0000
@@ -35,7 +35,7 @@ function drupal_load_updates() {
  * @param $module
  *   A module name.
  * @return
- *   If the module has updates, an array of available updates sorted by version. 
+ *   If the module has updates, an array of available updates sorted by version.
  *   Otherwise, FALSE.
  */
 function drupal_get_schema_versions($module) {
@@ -382,6 +382,10 @@ function drupal_uninstall_module($module
   module_load_install($module);
   module_invoke($module, 'uninstall');
 
+  // Remove all module's blocks.
+  db_query("DELETE FROM {blocks} WHERE module = '%s'", $module);
+  db_query("DELETE FROM {blocks_roles} WHERE module = '%s'", $module);
+
   // Now remove the menu links for all paths declared by this module.
   if (!empty($paths)) {
     $paths = array_keys($paths);
Index: modules/block/block.admin.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/block/block.admin.inc,v
retrieving revision 1.14.2.5
diff -u -p -r1.14.2.5 block.admin.inc
--- modules/block/block.admin.inc	24 Nov 2008 06:00:02 -0000	1.14.2.5
+++ modules/block/block.admin.inc	9 Mar 2010 15:10:23 -0000
@@ -340,6 +340,7 @@ function block_box_delete(&$form_state, 
 function block_box_delete_submit($form, &$form_state) {
   db_query('DELETE FROM {boxes} WHERE bid = %d', $form_state['values']['bid']);
   db_query("DELETE FROM {blocks} WHERE module = 'block' AND delta = '%s'", $form_state['values']['bid']);
+  db_query("DELETE FROM {blocks_roles} WHERE module = 'block' AND delta = '%s'", $form_state['values']['bid']);
   drupal_set_message(t('The block %name has been removed.', array('%name' => $form_state['values']['info'])));
   cache_clear_all();
   $form_state['redirect'] = 'admin/build/block';
Index: modules/block/block.install
===================================================================
RCS file: /cvs/drupal/drupal/modules/block/block.install,v
retrieving revision 1.8.2.2
diff -u -p -r1.8.2.2 block.install
--- modules/block/block.install	6 Jan 2009 15:46:36 -0000	1.8.2.2
+++ modules/block/block.install	9 Mar 2010 15:10:23 -0000
@@ -177,3 +177,25 @@ function block_schema() {
   return $schema;
 }
 
+/**
+ * @defgroup updates-6.x-extra Extra block updates for 6.x
+ * @{
+ */
+
+/**
+ * Cleanup orphan block's data.
+ */
+function block_update_6000() {
+  $ret = array();
+  // Cleanup for deleted custom blocks.
+  $ret[] = update_sql("DELETE FROM {blocks_roles} WHERE module = 'block' AND delta NOT IN (SELECT b.bid FROM {boxes} b)");
+  // Cleanup for uninstalled modules' blocks.
+  $ret[] = update_sql("DELETE FROM {blocks} WHERE module IN (SELECT s.name FROM {system} s WHERE s.type = 'module' AND s.status = 0 AND s.schema_version = -1)");
+  $ret[] = update_sql("DELETE FROM {blocks_roles} WHERE module IN (SELECT s.name FROM {system} s WHERE s.type = 'module' AND s.status = 0 AND s.schema_version = -1)");
+  return $ret;
+}
+
+/**
+ * @} End of "defgroup updates-6.x-extra"
+ * The next series of updates should start at 7000.
+ */