Sets the status of a node to 0 (unpublished).
$node: A node object.
$context: (optional) Array of additional information about what triggered the action. Not used for this action.
function node_unpublish_action($node, $context = array()) {
$node->status = NODE_NOT_PUBLISHED;
watchdog('action', 'Set @type %title to unpublished.', array(
'@type' => node_type_get_name($node),
'%title' => $node->title,
));
}