Some followup Questions:
1) How do we provision new UBB.threads accounts correctly since Drupal will be driving, not creating users via the UBB admin area?
2) What is the syntax for the magic cookie that Drupal should set when a Drupal login event happens successfully?
3) Is there a way to sync UserIDs and Passwords between Drupal and UBB? The front door will be mandatory Drupal and users will not be able to log into UBB. So could we possibly blank out the ability to log in via UBB?
4) Syntax for adjusting that cookie when a Drupal logout event occurs so UBB.threads no longer thinks the user is properly authenticated.