I feel that gadgets can be a proxy for people to feel superior to each other like with cars, sports teams, and purses. I don't know what people hope to get out of arguing about it other than entertainment perhaps.
The "I'm a Mac" ads are probably the most glaringly obvious case. The iPod dancer ads are another example of marketing that revolves around selling an image and lifestyle. Everybody does this kind of thing, Apple just does it better than most.
In addition to the "I'm a Mac" campaign mentioned by others, a recent example would be the "If you don't have an iPhone..." campaign: http://www.apple.com/iphone/gallery/ads.html