The answer as Apple replied: “We design the (product launch) keynotes so that the big reveal of the product happens around 40 minutes into the presentation. When the big image of the product appears on screen, we want the time shown to be close to the actual time on the audience's watches. But we know we won't hit 40 minutes exactly."
"So you add a couple of minutes?"
"Yeah! And for the iPhone, we made it 42 minutes. It turned out we were pretty accurate with that estimate, so for the iPad, we made it 41 minutes. And there you are - the secret of the magic time."