OK, I figured it out, but I have possibly used a sledgehammer to crack a nut here, so if I have missed some simple one-click setting on the admin panel somewhere, please tell me!
What I did was edit single.php, with the following code inside the loop, in a set of divs labelled postLinkPages which I haven’t actually seen doing anything else of use yet?? [Can someone tell me what they’re for?]
<?php if ( in_category('4') ) {
$category_link = get_category_link('4');
$my_query = new WP_Query('category_name=boards&posts_per_page=10');
while ($my_query->have_posts()) : $my_query->the_post();
?>
<span><a href="<?php the_permalink() ?>" title="<?php _e('Permalink to', 'Arjuna'); ?>
<?php the_title(); ?>"><?php the_title(); ?></a></span><br />
<? endwhile; ?>
<p><a href="<?php echo $category_link; ?>" title="Read more board reviews">Read all board reviews...</a><p>
<?php } ?>
(I’ve gone one step further than my original request, and it now just gives the first 10 listings for the boards category (id=4), if the post is of that category)
