Since that was posted we have also published an improved version using our uPWM hack, which gets you hardware PWM and better signal fidelity/accuracy and longer range.
Only thing with the uPWM is that the output signal is inverted, but we have also linked a simple circuit to handle that
... and since uPWM was posted we have come up with our A.IR Shield Photon, which features high quality IR components, configurabe IR Power, dual IR receiver & dual IR emitters, improved hardare PWM etc see