It was always planned that with a little bit of extra circuitry the PI would be used to control external devices, and this project, controlling a garge door, is exactly what the designers had in mind.
So what, you might think, a garage door opener is just an electric motor with some sensors telling it when to stop, and you would be right there are dozens of people out there doing that sort of thing every day, but the novelty here is the romote control. Its voice activated.
And then it gets really clever, the designer is using Siri on his iPhone, and a customisable toolkit, to send messages to the Pi. I can think of another dozen uses for that without taking breath, opening curtains, trigger a remote cat feeder, opening or locking the cat flap, opening vents on a green house, ok well maybe not a dozen, but you get the idea.
More details from the Register http://www.theregister.co.uk/2012/12/18/siri_talks_to_raspberry_pi_and_opens_door/