This isn't going to surprise anyone who has been anywhere near a digital video production environment, but those 'Laptop Hunters' ads are probably built on a Mac. The Filmmaker Sheila one seems especially ironic.
Wired reports that Microsoft's Ad agency, Crispin Porter + Bogusky is full of Macs including Bogusky himself who has two Macs on his desk (below). It is hard to prove that Macs are unneccesarily expensive when your agency won't even give them up. In other news, Microsoft laid of 3,000 people today.