Guardalos en un arreglo y luego lo imprimes:
Código PHP:
$sql = mysql_query("SELECT cName FROM ".DB_PREFIX."categories WHERE cParent = '".$cID."' ORDER BY cOrder ASC");
$cName[] = array();
while($r=mysql_fetch_array($sql)) { $cName[]=$r["cName"]; }
$todas=implode( ", ", $cName );
$cat_row = str_replace("{php=cat_name}", $todas, $cat_row);
echo $cat_row;
Saludos.