Adding in the ability to link to posts internally. Syntax: {% post_url 2010-07-21-name-of-post %}; useful for: [Some Link]({% post_url 2010-07-21-name-of-post %})

lib/jekyll/tags/post_url.rb

@@ -0,0 +1,38 @@
+module Jekyll
+
+  class PostComparer
+    MATCHER = /^(.+\/)*(\d+-\d+-\d+)-(.*)$/
+
+    attr_accessor :date, :slug
+
+    def initialize(name)
+      who, cares, date, slug = *name.match(MATCHER)
+      @slug = slug
+      @date = Time.parse(date)
+    end
+  end
+
+  class PostUrl < Liquid::Tag
+    def initialize(tag_name, post, tokens)
+      super
+      @orig_post = post.strip
+      @post = PostComparer.new(@orig_post)
+    end
+
+    def render(context)
+      site = context.registers[:site]
+      
+      site.posts.each do |p|
+        if p == @post
+          return p.url
+        end
+      end
+
+      puts "ERROR: post_url: \"#{@orig_post}\" could not be found"
+
+      return "#"
+    end
+  end
+end
+
+Liquid::Template.register_tag('post_url', Jekyll::PostUrl)