Add theme function to block

Sorry, should've cleaned that up before posting it.

Well, it's drupal_render rather than drupal_get_form. It's seeing the theme function automatically. This works for me, as a simple way to override it in template.php - I'm able to use something like:

function phptemplate_constant_contact_block_form($form) {
  global $user;

  drupal_render($form[0]);

  $output = '<div id="newsletter-block">';
  $output .= '<div id="email_text"></div>';
  $output .= '<div style="margin-bottom: 16px">';
  if ($form['email']) {
    $output .= drupal_render($form['email']);
  }
  else {
    $output .= '<div class="user-email">'. $user->mail .'</div>';
  }
  $output .= drupal_render($form[1]);

  $output .= drupal_render($form);
  $output .= '</div></div>';

  return $output;
}

etc...