pig_latin.rb

def translate(phrase)
  phrase.split.inject([]) do |final_pigs, word|
    char = word.split(//)
    if char[0].match(/[aeiou]/)
      final_pigs << "#{word}ay"
    else
      new_string = char
      until new_string[0].match(/[aeio]/)
        new_string << new_string.shift
      end
      final_pigs << new_string.join + "ay"
    end
    final_pigs
  end
end

Changes from the original:

• Use #inject; [] is the starting value for final_pigs, and word is all the elements within phrase.split; for more information, check the docs
• Use [0] instead of #at(0); I don't know any good reason to use #at
• Introduced an inconsistency by using string interpolation on line 5; for complex concatentation, many rubyists use this
• I'm not crazy about the new_string << new_string.shift line, but I can't think of a better way to do that now
• At the end of the #inject block, final_pigs is used as basically an implicit return of what the next final_pigs values should be; this is part of the usage of #inject

thanks @jcsalterego Really interesting use of inject! I really hadn't considered doing the summation of [ ] and word.