While watching the latest ads for Apple's new iPhone 4s, it occurred to me that in most of the shots only the bottom half of the actor's face is shown. You see their mouth, sometimes their nose, occasionally the eyes. As the ads progress, they show a little more of some faces, but it's clear that the focus is on the person speaking to the phone. This is incredibly important, obviously, as they're marketing a voice assistant feature, but the connection they are able to create is profound.
What I find interesting is that there's nothing to focus on in the shot other than what the person is actively doing. The tight shots create an intimacy with the viewer, as if you're eavesdropping on the people in the spot as they carry on a conversation with their phone.
The ads also begin and end with a POV shot looking down on the phone. The effect of these bookend shots is to place the viewer into the context of using the device, and it's remarkably effective. One can instantly imagine actually using the new feature of the phone that's just been demonstrated.