code: def getContactUIDForUser(self):
          
          user = self.REQUEST.AUTHENTICATED_USER
          user_id = user.getUserName()
          r = self.portal_catalog(
              portal_type='Contact',
              getUsername=user_id
          )
          if len(r) == 1:
              return r[0].UID
docs: get the UID of the contact associated with the authenticated
              user