Rakefile

namespace :tag do
  desc "Tag last post"
  task :last do
    system("./_scripts/tagposts last")
  end
  
  desc "Re-tag all posts"
  task :all do
    system("./_scripts/tagposts all")
  end
end

desc "Deploy to production"
task :deploy => [:generate, 'tag:last'] do
  system("rsync -avz --delete _site/ lukeredpath.co.uk:#{SITE_ROOT}")
end

site.rb

require 'jekyll'

module Site
  def self.load
    config = Jekyll.configuration('source' => File.join(File.dirname(__FILE__), *%w[..]))
    Jekyll::Site.new(config).tap { |site| site.read }
  end
end

tagger.rb

require File.join(File.dirname(__FILE__), *%w[site])
require 'rubygems'
require 'www/delicious'

class Tagger
  def initialize(api, site)
    @api, @site = api, site
  end
  
  def tag_all
    tag(@site.posts)
  end
  
  def tag_last
    tag([@site.posts.last])
  end
  
  def tag(posts)
    posts.each do |post|
      next if post.tags.empty?
      
      if @api.posts_get(:url => url_for_post(post), :tag => default_tag).any?
        @api.posts_delete(url_for_post(post))
      end
        
      @api.posts_add(
        :url   => url_for_post(post),
        :title => post.data['title'],
        :tags  => [post.tags, default_tag].flatten
      )
      puts "➜ Tagged post '#{post.data['title']}'."
    end
  end
  
  def self.connect(username, password, site = Site.load)
    api = WWW::Delicious.new(username, password)
    new(api, site)
  end
  
  private
  
  def url_for_post(post)
    return @site.config['base_url'] + post.url
  end
  
  def default_tag
    "@#{URI.parse(@site.config['base_url']).host}"
  end
end

tagposts.rb

#!/usr/bin/env ruby
require File.join(File.dirname(__FILE__), *%w[.. _lib tagger])
require 'yaml'

delicious_config = YAML.load(File.open('_delicious.yml'))['delicious']
tagger = Tagger.connect(delicious_config['username'], delicious_config['password'])

if ARGV[0] == 'all'
  tagger.tag_all
elsif ARGV[0] == 'last'
  tagger.tag_last
else
  puts "Usage: tagger (all|last)"
  exit 1
end  

The series of scripts that I use to tag my blog posts automatically in Delicious. See here for more information.

My Delicious credentials are stored outside of the scripts, in the root of my site in a file called delicious.yml.

If you have a newer Delicious account, you'll need to modify this to work with OAuth.

As to where this files go, I structure the root of my Jekyll site like this (underscore prefixed dirs are not added to the generated output):

_lib/ # support scripts like site.rb and tagger.rb
_scripts/ # scripts like tagposts