gistfile1.rb

module Kernel
  def eventually(timeout = 1.0, start = Time.now, exception = nil, &block)
    throw exception || Timeout::Error if Time.now > (start + timeout)
    begin
      return true if block.call
    rescue RSpec::Expectations::ExpectationNotMetError => exception
      EM.next_tick {
        eventually(timeout, start, exception, &block)
      }
    end  
  end
end

# Usage:

eventually { something.should == true }