Get more info - eg, categories

Hi. How do I get the categories to display on the results page? Just like they do on the default WP search.

I have got the date to display, using (line 260ish)

$date = date('jS F Y',$post[post_published_stamp]);
$content .= '<small>' . $date . '</small>';

But I can't get the categories to display. I have tried

foreach((get_the_category($post)) as $category) {
$content .= '<small' . $category->cat_name . '"</small>';
}

But that isn't doing anything.

Good plugjn by the way. Simply to setup and not resource hungry.
Thanks