We have seen several different add-on lenses designed to enhance the iPhone camera, but these versions ditch the case in favor of magnetic mounts. There are also three different lenses to choose from.
Because the iPhone has a plastic case, a self-adhesive ring with a magnet must first be affixed to the area around the camera lens. After that, it's a simple matter of bringing the add-on lens in contact with the magnet. In fact, the wide angle, telephoto and fish-eye lenses can be used on just about any device with appropriately-sized webcams and cameras. How well the lenses work is unknown, but at least they won't break the bank at $17 apiece. [USB Fever via Gear Diary]