Add contextual link to block

gistfile1.php

<?php

// See http://dominiquedecooman.com/blog/drupal-7-tip-add-contextual-links-anything
// See http://drupal.org/node/1089922

// hook_menu
// Menu item must have 'context' set to MENU_CONTEXT_PAGE | MENU_CONTEXT_INLINE

function mymodule_menu() {
  return array(
    'admin/mymodule/myblock' => array(
      'title' => "My Block",
      'page callback' => 'mymodule_myblock_callback',
      'type' => MENU_LOCAL_TASK,
      'weight' => 15,
      'context' => MENU_CONTEXT_PAGE | MENU_CONTEXT_INLINE, // This is the important part !!
      'access arguments' => array('administer mymodule')
    ),
  );
}

// Block view callback
// Contextual links must be in $block['content']['#contextual_links']
function mymodule_block_myblock() {
  return array(
    'subject' => t("My Block"),
    'content' => array(
      '#markup' => "My block content",
      '#contextual_links' => array(
        'mymodule' => array(
          'admin/mymodule/myblock',
          array('')
        ),
      ),
    ),
  );
}