set_language_by_hostname.rb

# IN app/controllers/application.rb

require 'uri'

before_filter :set_language

# ...

# Set language by hostname (.com => 'en', .cz => 'cz')
def set_language
  Gibberish.current_language = URI.parse(request.url).host.split('.').last.gsub(/com/, 'en')
  logger.debug "Language set to '#{Gibberish.current_language}'" 
end