[MarkFL]

First, you may combine the 3 lines:

PHP Code:

vB_Template::preRegister('header', array('notifications_menubits' => $notifications_menubits));
vB_Template::preRegister('header', array('notifications_total' => $notifications_total));
vB_Template::preRegister('header', array('ubermenu' => $ubermenu)); 


as follows:

PHP Code:

vB_Template::preRegister('header', array('notifications_menubits' => $notifications_menubits, 'notifications_total' => $notifications_total, 'ubermenu' => $ubermenu)); 


However, I am thinking this is more along the lines of what you want to do:

PHP Code:

$templater = vB_Template::create('ubermenu');
    $templater->register('notifications_menubits', $notifications_menubits);
    $templater->register('notifications_total', $notifications_total);
$ubermenu = $templater->render();
vB_Template::preRegister('header', array('ubermenu' => $ubermenu)); 


This way you are registering the two variables your "ubermenu" template needs to render its output correctly, and then you can register that output (stored in $ubermenu) for use in the header template.