Ok... I took a whack at making this work in J! 1.5.1, but I think it may be beyond my shaky grasp of the differences between J! 1.0x and J! 1.5x and php in general

. Basically we never messed with 1.0x after we decided that the vB bridges were too unstable, so I don't know that much about 1.0x at all.
The function call mosMainbody doesn't exist in 1.5, I took a stab at it but I'm not at all sure I've got it right.
I also had to modify the plugin a bit, so that it looks more like this:
Code:
define( '_JEXEC, 1 );
$myjoomlapath = $vbulletin->options['dyn_joomla_path'];
require_once( $myjoomlapath.'/configuration.php' );
require_once( $myjoomlapath.'/includes/joomla.php' );
require_once( JPATH_SITE .'/includes/frontend.php' );
require_once( JPATH_SITE .'/includes/sef.php' );
$mainframe = new mosMainFrame( $database, '', '.' );
$mainframe->initSession();
ob_start();
include_once(JPATH_SITE . '/templates/' . $mainframe->getTemplate(). '/vbulletin/head.php');
$myjoomladhead = ob_get_contents();
ob_clean();
include_once(JPATH_SITE . '/templates/' . $mainframe->getTemplate(). '/vbulletin/header.php');
$myjoomladheader = ob_get_contents();
ob_clean();
include_once(JPATH_SITE . '/templates/' . $mainframe->getTemplate(). '/vbulletin/footer.php');
$myjoomladfooter = ob_get_contents();
ob_end_clean();
Not sure if that's right or not?
If you *do* play with it in 1.5, let us know? Given that we're working with media mogul too, it'd be a real easy implementation for us if you provide updated templates based on RT's MM.
I'll keep on banging away on it to see if I can figure out what's wrong... And post back if I make any headway.
James and Susan