I found this, is this proper?
http://www.wprecipes.com/get-tags-specific-to-a-particular-category-on-your-wordpress-blog
<?php
query_posts('category_name=html');
if (have_posts()) : while (have_posts()) : the_post();
$posttags = get_the_tags();
if ($posttags) {
foreach($posttags as $tag) {
$all_tags_arr[] = $tag -> name;
}
}
endwhile; endif;
$tags_arr = array_unique($all_tags_arr);
?>
<ul>
<?php
foreach($tags_arr as $tag){
echo '<li>'.$tag.'</li>';
}
?>
</ul>
<?php wp_reset_query(); ?>
Here is updated code for when someone along the way comes to a similar question. This example uses a better core wordpress function to simplify the process. Just change the category name. If there is a simpler way, feel free to chime in.
<?php query_posts('category_name=html');
if (have_posts()) : while (have_posts()) : the_post();
if( get_the_tag_list() ){
$posttags = get_the_tag_list('<ul><li>','</li><li>','</li></ul>');
}
endwhile; endif;
echo $posttags;
wp_reset_query();
?>