Thematic conditionals on category loop with an override.

gistfile1.txt

// override the category loop
// http://thematictheme.com/forums/topic/post-listing-without-thumbnails/
function childtheme_override_category_loop() {
    if ( is_category('blog') ) {
        while ( have_posts() ) : the_post();

            // your custom blog loop
            // reference thematic/library/extensions/content-extensions.php where the original loop resides.

        endwhile;
    } else {
        while ( have_posts() ) : the_post();

            // a custom loop for everything else
        
        endwhile;
    }
}