Voting starts in March for the Drupal Association Board election.
..found some more time :-)
You should write the fieldset in "function theme_pollfield" like that:
... $form = array(); $form[$fieldname] = array( '#type' =>'fieldset', '#title' =>t('Extra cck fields'), '#collapsible' =>TRUE, '#collapsed' =>TRUE,
because if someone uses vertical tabs this cck field is better included. ( Now the fieldset is not displayed as fieldset in vertical tabs)