function is_ancestor_cat($ancestor, $descendant){
  $ancestor = (string) $ancestor;
  $desc_id = (string) $descendant;
  $child_cats = get_term_children( (string) $ancestor, 'category');
  if($ancestor == $descendant){
    return true;
  }
  else if(!count($child_cats)){
    return false;
  }
  else{
    $is_child = false;
    foreach($child_cats as $cat_id){
      if($cat_id == $desc_id){
        $is_child = true;
        break;
      }
      else{
        $is_child = $is_child || is_ancestor_cat($cat_id, $descendant);
      }
    }
    return $is_child;
  }
}

What this code does is that is grabs all the children for the ancestor category then checks them against the descendant category, it will keep recursing until it hits the leaf nodes and returns a boolean value.
Here it is in action in my template file category.php:

//Check if we are in a category
if(is_category()){
  $ancestor_cat_id = 43;
  //Lets get the current category we are in
  $cur_cat_id = get_cat_id( single_cat_title("",false) );
  $is_ancestor = false;
  //Check if we are in the ancestor category
  $is_ancestor = is_ancestor_cat($ancestor_cat_id, $cur_cat_id);

  //If it is an ancestor, use a specific template
  if($is_ancestor){
   include(TEMPLATEPATH.'/category-43.php');
  }
  //Use the default template
  else{
   include(TEMPLATEPATH.'/category-default.php');
  }

}

if ( function_exists('register_sidebar') )
    register_sidebar(array(
        'before_widget' => '<div class="sidebar-box">',
    'after_widget' => '</div></div>',
 'before_title' => '<h2><span>',
        'after_title' => '</span></h2><div class="sidebar-box-inside">',
    ));

This isn’t exacly what I wanted as it will apply this to all of my widgets. So after a little more snooping around the web I noticed a WP filter that does what I want. The fitler is called dynamic_sidebar_params and it is called like this:

add_filter('dynamic_sidebar_params', 'my_function_callback');

Where my_function_callback is the name of your function. In my case I called it like this, in functions.php:

add_filter('dynamic_sidebar_params', 'sidebar_styling');

Next I had to figure out a way to style each element uniquely. I decided that the widget name would be a good identifier. Luckily this filter will pass you a field called widget_id, which has a sanitized version of the name which can be used for your CSS identifier. Here is what the params variable looks like:

Array
(
    [name] => Sidebar 1
    [id] => sidebar-1
    [before_widget] => <div class="sidebar-box">

    [after_widget] => </div></div>
    [before_title] => <h2><span>
    [after_title] => </span></h2><div class="sidebar-box-inside">
    [widget_id] => recent-posts
    [widget_name] => Recent Posts
)

Now that we have that ID, it is a simple function to write:

function sidebar_styling($params){
  $params[0]['before_title'] = '<h2 id="sidebar-'.@$params[0]['widget_id'].'"><span>';
  return $params;
}

Now WP will output the unique id for each heading and we can just style it appropriately. I used a big sprite to save resources:

Dynamic Sidebar

#sidebar-recent-posts span{display: none;}
#sidebar-recent-posts{
  background: transparent url(images/sidebar-titles/dynamic-sidebar.png) 0 0 no-repeat !important;
}
#sidebar-twitter-tools span{display: none;}
#sidebar-twitter-tools{
  background: transparent url(images/sidebar-titles/dynamic-sidebar.png) 0 -41px no-repeat !important;
}
#sidebar-categories span{display: none;}
#sidebar-categories{
  background: transparent url(images/sidebar-titles/dynamic-sidebar.png) 0 -82px no-repeat !important;
}
#sidebar-archives span{display: none;}
#sidebar-archives{
  background: transparent url(images/sidebar-titles/dynamic-sidebar.png) 0 -123px no-repeat !important;
}
#sidebar-links span{display: none;}
#sidebar-links{

  background: transparent url(images/sidebar-titles/dynamic-sidebar.png) 0 -164px no-repeat !important;
}

That is all there is, you can see the results on the page you are reading.
I found these articles/sites helpful:

• Dynamic Widget Classes for use in CSS

After some initial research I discovered that this markdown code is called “shortcode” in WP terminology. They have a whole Shortcode API. Now it was just a matter of finding the correct functions to get the shortcode to render.

I wanted to create a special template for the category, essentially a photo blog, so that it would look different from the other categories. This is pretty straightforward, just create a new file called category-id.php, where id is the id number of your category. In my case it was category-40.php. The next step was to copy all the code from category.php and paste it into category-40.php.

When displaying the post’s excerpt, Wordpress uses a function called the_excerpt(). Here it is in the default sandbox template:

the_excerpt(''.__('Read More <span class="meta-nav">&raquo;</span>', 'sandbox').'') ;

The problem with the_excerpt is that is echoes the excerpt directly to the screen. In order to return the excerpt value as a string we need to use get_the_excerpt(). Next after checking the shortcode API, I discovered a function that will run all the shortcodes on a given string and return the output as a string, do_shortcode().

So all we need to do now is combine these two functions, and move it into the template:

echo do_shortcode(get_the_excerpt());

And there it is!