Sort posts in page template by category, then title

Here is some sample code that I think will work, but you should probably modify to handle the ‘posts not found’ case. Put this in your functions.php:

<?php function mam_posts_fields ($fields) {
   global $mam_global_fields;
   if ($mam_global_fields) $fields = "$fields, $mam_global_fields";
   return $fields;
}
function mam_posts_join ($join) {
   global $mam_global_join;
   if ($mam_global_join) $join = "$join $mam_global_join";
   return $join;
}
function mam_posts_orderby ($orderby) {
   global $mam_global_orderby;
   if ($mam_global_orderby) $orderby = $mam_global_orderby;
   return $orderby;
}
add_filter('posts_fields','mam_posts_fields');
add_filter('posts_join','mam_posts_join');
add_filter('posts_orderby','mam_posts_orderby');
?>

And use this in your template:

<?php
    $mam_global_fields = 'mmt.name as catname';
    $mam_global_join = "JOIN $wpdb->term_relationships mmtr
       ON ({$wpdb->posts}.ID = mmtr.object_id)
    JOIN $wpdb->term_taxonomy mmtt
       ON (mmtr.term_taxonomy_id = mmtt.term_taxonomy_id AND mmtt.taxonomy = 'category')
    JOIN $wpdb->terms mmt ON (mmtt.term_id = mmt.term_id)
    ";
    $mam_global_orderby = 'catname ASC, post_title ASC';
    echo '<h2>Articles By Category</h2>';
    $args = array(
      'caller_get_posts' => 1,
      'posts_per_page' => -1,
      'category__not_in' => array(20,27,28,33),
   );
   $catname = '';
   query_posts($args);
    if (have_posts()) : while (have_posts()) : the_post();
       if ($catname != $post->catname) {
         $catname = $post->catname;
         echo "<br /><b>$catname</b>";
       }
       echo "<br />&nbsp; - ";?>
       <a href="<?php the_permalink(); ?>"><?php the_title(); ?></a>
    <?php endwhile; endif; ?>