example [datapipe.com.]. Notice the girl on the right is shot from above. Diamond is doing the same with all there Rio MP3 player ads. I've seen this technique used so much lately that it is almost a trend. Why? What's the power in the overhead shot? At first I thought it must be a perspecitive to give the teenage set the feeling they are looking down a womans top - seriously - that is the only thing I can come up with.
I've noticed the same thing in the UK - mostly for games and consoles - bumps the teenage market/looking down a girl's top theory into the upper percentile, as Brett says. Makes me want the product! ;)
I ask an ad guru friend of mine in marketing at a large computer manufacture. He says the theory is that the person is literally looking up to you. Often these shots are done with the product in the hand offering it to you. It is suppose to make you feel important and that the company or product bestows respect upon you. People like to own products they are proud of, yet have power over. The looking up to you theory is in effect, the product bowing before you. Very Freudian, but must be effective.