capistrano recipe for moving public files to s3

generate_and_deploy_assets.rb

desc "Generate and deploy assets"
task :deploy_assets, :roles => :app do
  # get the previous timestamp
  old_timestamp = File.read("config/deploy_timestamp").to_i rescue 0
  
  # generate timestamp into config/deploy_timestamp
  timestamp = Time.now.to_i
  File.open("config/deploy_timestamp", 'w') do |f|
    f.write(timestamp)
  end
  
  # generate minified JS and CSS
  system('rake asset:packager:build_all')
  
  # sync local public/ directory to S3 bucket
  # the S3 bucket directory should be the timestamp generated above
  require 'right_aws'
  
  s3 = RightAws::S3.new(access_key_id, secret_access_key)
  bucket = s3.bucket('a-bucket')
  
  put_count = 0
  copy_count = 0
  Dir.glob('public/**/*').each do |f|
    next if File.directory?(f)
    
    key = "#{timestamp}/#{f.gsub(/public\//, '')}"
    
    if File.new(f).mtime.to_i > old_timestamp
      puts "putting #{f} into S3 as #{key}"
      bucket.put(key, File.read(f), {}, 'public-read')
      put_count += 1
    else
      old_key = bucket.key("#{old_timestamp}/#{f.gsub(/public\//, '')}")
# comment this out until I can replace RightAWS::S3 with something that supports 
# S3 ACL URI groups.
      #if old_key.exists?
      #  puts "copying #{old_key} to #{key}"
      #  old_key.copy(key)
      #  copy_count += 1
      #else
        puts "putting #{f} into S3 as #{key}"
        bucket.put(key, File.read(f), {}, 'public-read')
        put_count += 1
      #end
    end
  end
  puts "done. #{put_count} files uploaded, #{copy_count} keys copied"
  
  # add and commit the config/deploy_timestamp file
  system('git add config/deploy_timestamp')
  system('git commit -m "deploy_assets complete, updating timestamp"')
  system('git push')
end

Does this delete old files off S3 or just sync the files in the public folder?