Returning info from Drupal updates
Drupal update hooks can return info about queries run - and this is well documented.
If you want to return other informative messages about updates - just use the same format as returned by http://api.drupal.org/api/function/update_sql/6
<?php
array('success' => $result !== FALSE, 'query' => check_plain($sql));
?>
So you might have an update hook that looks like.
<?php
/**
* Drush picks up notes from here
* Will update myvar to new val because...
*/
function mymodule_update_6101(){
$items = array();
$myval = "foo":
variable_set('myvar', $myval');
$items[] = array('success' => TRUE, 'query' = "updated variable myvar to $myval because...");
return $items;
}
?>
This way all changes can be logged to the update page.