Ok, figuring out the newest member is the last thing index.php does before spitting out the HTML. Here's the code.
PHP Code:
// get total members and newest member from template
$userstats = unserialize($datastore['userstats']);
$numbermembers = vb_number_format($userstats['numbermembers']);
$newusername = $userstats['newusername'];
$newuserid = $userstats['newuserid'];
Now, if you can run newuserid through the is_member_of function you could prune out new users who's registration is pending confirmation. However, I don't know how you would go back through the list of users to find the most recent confirmed member.