The iPhone 4 and iPhone 4S have arguably the best smartphone cameras in the market. The wide availability of various photography and image editing apps on iOS also makes these smartphones ideal everyday cameras. Bitplay recently introduced their SNAP line of iPhone cases which really put the iPhone's camera front and centre.
Bitplay's SNAP cases are available in black, white and silver (which is two-toned and more like vintage cameras) but the effect isn't purely cosmetic. These cases come with a working shutter button. Bitplay SNAP sells for $49 and is availabe from Dynamism.com