<?php
$querystr = "
SELECT wposts.*
FROM $wpdb->posts wposts, $wpdb->postmeta wpostmeta
WHERE wposts.ID = wpostmeta.post_id
AND wpostmeta.meta_key = 'date_field'
AND wpostmeta.meta_value="03/11/2010"
AND wposts.post_status="publish"
AND wposts.post_type="post"
ORDER BY wposts.post_date DESC
";
$pageposts = $wpdb->get_results($querystr, OBJECT);
?>
Then you would access $pageposts as an object