org_converter.rb

module Jekyll
  # Convert org-mode files.
  require 'org-ruby'
  class OrgConverter < Converter
    safe true

    def setup
      # No-op
    end

    def matches(ext)
      ext =~ /org$/i
    end

    def output_ext(ext)
      ".html"
    end

    def convert(content)
      setup
      Orgmode::Parser.new(content).to_html
    end
  end
end

You can put the plugin here: ./_plugins/org_converter.rb

@stardiviner If you were asking how it works, I believe it leverages org-ruby.