```ruby
atom_feed(:url => formatted_posts_url(:atom)) do |feed|
feed.title(@category.name)
feed.updated(@posts.first ? @posts.first.created_at : Time.now.utc)
for post in @posts
feed.entry(post) do |entry|
entry.title(post.title)
entry.content(post.body_html, :type => 'html')
entry.updated post.updated_at
for tag in post.tags
entry.category :term => url_for(tag), :label => tag.name
end
end
end
end
```