I understand that most search engines do not pay ant attention to key words anymore, but they will pickup the descriptions on the site. in 1.5.4 default template the description has been killed instead of the key words.
//$this->output('<META NAME="description" CONTENT="'.$this->content['description'].'"/>'); and the key words function is open.
$this->output('<META NAME="keywords" CONTENT="'.$this->content['keywords'].'"/>');
if you want the descriptions to show on the index and place some in your admin section just remove the // from
//$this->output('<META NAME="description" CONTENT="'.$this->content['description'].'"/>');