The lens has a magnetic ring on the rear and then you apply a ring as well to the camera on your phone that has some adhesive in the rear of it.
Some of you will ask where I got it from. Well. There are several types on the internet of the same brand, but this one seems to give the best picture and less blurriness around the edges. It rocks.
Only issue I see is the flash will be semi-blocked and might cause odd lighting. Since I came from the Samsung Vibrant it won't be such a big deal to turn the flash off for the time being.
Some sample photos with the Samsung Vibrant and the fish eye. I'll get some better shots soon with the G2x. The Vibrant's cam wasn't the best either. :/