its easy to make Portal System, aint that hard.
if you want latest threads to be displayed, you can just make it by using PHP file (you know that the output will be html eventually but you have to use php for it), and read the latest threads for example:
$threadlist = $DB_site->query("SELECT * FROM thread ORDER BY `threadid` DESC LIMIT 10");
while ($tdlist = fetch_array($threadlist))
{
$title = $tdlist['title'];
$forum = $tdlist['forumid'];
.
.
.
eval('$tdlistbit .= "' . fetch_template('tdlistbit') . '";');
}
eval('$tdlist = "' . fetch_template('tdlist') . '";');
this is example will present you 10 Last Threads who posted in the forum, you can modify it to give you by forum, more threads \ less.. etc'.
just simple coding, and you get the perfect Portal system, that you want and exacly with your needs.
JUST to integrate vBB with your own portal system you have to call global.php (require_once('./forum_folder/global.php');)
Hope i gave ya prespective how it should look

its for vB3.0.x not 3.5.x

enjoy!