Synchronize roster in Drupal?

Another option for user relationship/roster synchronization might be to have Drupal make the XMPP calls directly:

1) modify hook_user_relationships($op) implementation to call the server directly.
2) if the call fails, however, we'd need to store a flag so it's called later on cron, so we don't hang up the current page request.
3) cron would need to take care of any hanging synchs to do. we might need an admin-configurable variable to limit how many synchs to attempt.
4) once it's working, we'd remove the sub/unsub from js.
5) alternatively, allow the admin to select which type of synch to perform.