formtemplate.php

<?php
function modulename_theme($existing, $type, $theme, $path) {
  return array(
    'formtemplate_horizontal' => array(
      'arguments' => array('form' => NULL),
    ),
  );
}

function theme_formtemplate_horizontal($form) {
  $output = '<table class="formtemplate-horizontal"><tr>';
  foreach (element_children($form) as $key) {
    if (in_array($form[$key]['#type'], array('submit', 'button'))) {
      $output .= '<td class="valign-middle">';
    }
    else {
      $output .= '<td>';
    }
    $output .= drupal_render($form[$key]) .'</td>';
  }
  $output .= '</tr></table>';
  return $output;
}

/*
css

table.formtemplate-horizontal {
  width: 0;
  border-collapse: none;
} 

table.formtemplate-horizontal .valign-middle {
  vertical-align: middle;
}
*/
?>