bt_translation.rb

#!/usr/bin/env ruby

# Riddle at http://bt.tumblr.com/post/202253034

# Lower case letters
letters            = ('a'..'z').to_a
translated_letters = letters.dup
12.times { translated_letters.push translated_letters.shift }

# Upper case letters
upcase_letters            = ('A'..'Z').to_a
translated_upcase_letters = upcase_letters.dup
12.times { translated_upcase_letters.push translated_upcase_letters.shift }

# Translation table
translation = Hash[*(translated_letters.zip(letters) + translated_upcase_letters.zip(upcase_letters)).flatten]

puts DATA.read.gsub(/./) { |c| translation[c] || c }

# The number of songs on the album is the number of
# zodiac-signs, the number of aposteles, and the
# number of balls that fit around one ball of the
# same size

__END__
Ftq zgynqd ar eazse az ftq mxngy ue ftq zgynqd ar
lapumo-eusze, ftq zgynqd ar mbaefqxqe, mzp ftq
zgynqd ar nmxxe ftmf ruf mdagzp azq nmxx ar ftq
emyq eulq