[Lynne]

Actually, I just relooked and saw it's already there in the cache (and I don't know what I was thinking of using that function - middle of the afternoon brain fart or something). You can see it totaling up the posts in the function, just grab the total for that forum and do what you want with it:

if (is_array($vbulletin->forumcache))
{
    foreach ($vbulletin->forumcache AS $forum)
    {
        $totalthreads += $forum['threadcount'];
        $totalposts += $forum['replycount'];
        if ($forum['forumid'] == xx) $forumpostcount = $forum['replycount'];
    }
}