I installed the 7.x version of Arthemia and was scratching my head trying to get the breadcrumbs to show up. Turns out some code in template.php was always hiding the breadcrumb.

In template.php, the old function looked like this:

/**
 * Return a themed breadcrumb trail, but only if there is more than one link in it.
 */
function arthemia_breadcrumb($breadcrumb) {
  if (count($breadcrumb) > 1) {
    return '<div class="breadcrumb">'. implode(' &rsaquo; ', $breadcrumb) .'</div>';
  }
}

I am new to Drupal but have lots of PHP experience. Not sure if this is a deeper DRUPAL core problem or not but this line of code will always be false because $breadcrumb arrives to this function as a 2 level associative array. The first level is always, as far as I can tell, just one array with a key of "breadcrumb", the second containing all the breadcrumb information.

I changed the code to the following and it worked great.

function arthemia_breadcrumb($breadcrumb) {
  if (count($breadcrumb["breadcrumb"]) > 1) {
    return '<div class="breadcrumb">'. implode(' &rsaquo; ', $breadcrumb["breadcrumb"]) .'</div>';
  }
}