Same loop, different formatting depending on category?

I’ve gotten as far as thinking it’ll be a conditional tag inside the loop, but I’m having a hard time getting it to determine whether a specific post is from one category or another:

<?php
query_posts('&showposts=10');

global $more;
// set $more to 0 in order to only get the first part of the post
$more = 0; 

// the Loop
while (have_posts()) : the_post();
?>

		<?php if(is_category(12)) { ?>
			<li <?php post_class() ?>>
            		<div class="title">

        		<h2 id="post-<?php the_ID(); ?>">BLAH<a href="<?php the_permalink() ?>" rel="bookmark" title="<?php the_title_attribute(); ?>"><?php the_title(); ?></a></h2>

        		<h3>Posted in: <span><?php the_category(', ') ?></span></h3>

        		</div> 

			<!-- .post --></li>

		<?php } else { ?>

	         	<div class="title">

                        <h2 id="post-<?php the_ID(); ?>"><a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>"><?php the_title(); ?></a></h2>

                        <h3>Posted in: <span><?php the_category(', ') ?></span></h3>

                        </div> 

		<?php } ?>

Right now I’d want it so that in the loop, if the category is 12, then print the word “BLAH” ahead of the title (just as a test). Currently it’s not working. I have a feeling it’s because is_category checks to see if the entire PAGE is from a category, not just that specific post.

Any guidance is much appreciated.