This is now installed on my forums. 8)
Edit: Today I banned a test account from my forums out of curiousity for what being banned from a vBulletin forum looks like and I saw a welcome header being displayed on my test account.
This can be fixed by changing the Welcome Headers [Alteration] plugin to:
PHP Code:
if ($vbulletin->userinfo['usergroupid'] != 9)
{
eval('$welcomeheaders = "' . fetch_template('welcome_headers') . '";');
}