From the official site:
"The olloclip is a quick-connect lens solution for the iPhone 4 that includes fisheye, wide-angle and macro lenses in one small, convenient package that easily fits in your pocket.
Nestled in the palm of your hand, the olloclip connects to the iPhone within seconds so you’ll be sure to capture the image you want…if you don’t see the picture you’re looking for just flip it over to switch lenses.
The Fisheye lens captures approximately a 180 Degree field-of-view and produces some striking images.
The Wide-Angle lens is great for when you need that extra field of view, approximately double that of the normal IPhone.
The Macro lens applies roughly a 10X multiplier and allows you to focus the iPhone within 12-15mm of the subject.
The Macro lens is cleverly concealed within the olloclip and can be accessed by unscrewing the Wide-Angle lens that is normally attached to it."
Thanks to my great friend Stefanos Karagos of Xplain for introducing me to the Olloclip (among many other cool gadgets and apps).