simple_desktops.rb

#!/usr/bin/env ruby
require 'FileUtils'

url = 'http://feeds.feedburner.com/simpledesktops\?format\=xml'
dir = Dir.home + '/Pictures/Wallpaper/'

FileUtils.mkdir_p(dir) unless Dir.exists?(dir)

wallpapers = `curl -s #{url}  \
              | grep .static  \
              | cut -f4 -d';' \
              | cut -f2 -d'"' \
              | cut -f1-4 -d'.'`.split("\n")

wallpapers.each do |wallpaper|
  output = dir + wallpaper.split("/").last
  `curl -s -o #{output} #{wallpaper}` if not File.exists?(output)
end

Dir.rmdir(dir) if Dir.entries(dir).join == "..."