Don't Growl, Say.

.growl

module Growl
  def notify_with_say(message = nil, options = {}, &block)
    message = message.gsub(/in\s*[0-9\.]+\s*seconds$/, '')
    `say -v Virginie "#{message}"`
    return
  end

  alias_method_chain :notify, :say

  module_function :notify
end

spec_helper.rb

# Try to load a growl override
begin
  load File.expand_path("../../", __FILE__) + '/.growl'
rescue LoadError
end