You meant a new column in the forum table.
Well, the $foruminfo array is populated in the /global.php file which calls the fetch_foruminfo function (located in the /includes/functions.php) to execute the sql query below, so i believe there shouldn't be a problem loading the new custom columns.
global.php is called at the very beginning of almost each file that has an output.
PHP Code:
$vbulletin->forumcache["$forumid"] = $vbulletin->db->query_first_slave("
SELECT forum.*, NOT ISNULL(podcast.forumid) AS podcast
FROM " . TABLE_PREFIX . "forum AS forum
LEFT JOIN " . TABLE_PREFIX . "podcast AS podcast ON (forum.forumid = podcast.forumid AND podcast.enabled = 1)
WHERE forum.forumid = $forumid
");
May someone correct me if im wrong.