Rollei has announced four add-on converter lenses for the Apple iPhone 3G/4/4s. The lenses include 12x and 9x telephoto optics, a .5x wide-angle converter, and a .28x fisheye converter. The lenses are available in Europe now; it's not clear whether they will be officially imported into North America.
The lenses mount to the iPhone via a hard case or bracket, which appears to be included with each lens.
Suggested retail rices range from €19.99 for the .28x fisheye converter to €49.99 for the 12x telephoto optic.