En Twentyten viene un código que funciona perfectamente, y no es tan complicado...
Código PHP:
Ver original<?php
$images = get_children
( array( 'post_parent' => $post->ID, 'post_type' => 'attachment', 'post_mime_type' => 'image', 'orderby' => 'menu_order', 'order' => 'ASC', 'numberposts' => 999 ) ); if ( $images ) :
$total_images = count( $images ); $image_img_tag = wp_get_attachment_image( $image->ID, 'thumbnail' );
?>
<div class="gallery-thumb">
<a class="size-thumbnail" href="<?php the_permalink(); ?>"><?php echo $image_img_tag; ?></a>
</div><!-- .gallery-thumb -->
<p><em>
<?php printf( _n
( 'This gallery contains <a %1$s>%2$s photo</a>.', 'This gallery contains <a %1$s>%2$s photos</a>.', $total_images, 'twentyten' ), 'href="' . get_permalink
() . '" title="' . esc_attr
( sprintf( __
( 'Permalink to %s', 'twentyten' ), the_title_attribute
( 'echo=0' ) ) ) . '" rel="bookmark"', number_format_i18n( $total_images )
); ?></em></p>
<?php endif; ?>
Eso lo pones en category.php... Saludos.
PD: Por casualidad Thesis es de pago???