This class returns you an object that you can foreach() loop through, passing regular WordPress get_posts() args, and the results will be grouped by category or custom taxonomy. It's designed right now to work with posts in only one category [taxonomy term].
Usage:
$args = array(
'taxonomy' => 'my_taxonomy',
'post_type' => 'my_type',
);
$p = sld_groupby_category( $args );
foreach ( $p as $post ) :
if ( sld_groupby_category_changed( $post ) )
echo '<h1>' .sld_groupby_category_name( $post ). '</h1>';
the_title(); // etc
endforeach;