It's a flexible selective focus 50mm lens (see www.lensbabies.com). There's a movable "sweet spot" where the image is sharp, and the rest gets a "love it or hate it" radial blur effect. The version 3 allows you to lock the bellows in place, so it's usable for macro stuff (with a couple of screw-on magnifiers). I'm just beginning to play with it (these could be a lot better!) but I can see the potential for some interesting results.
