Usually, before you take a photo you have to focus. Not with Lytro. Instead of recording the image data with pixels, Lytro uses records the direction and intensity of the light rays (the Lytro website does a better job of explaining than I ever will). This means you can change the depth of the field and the plane of focus after taking a photo (within a range).
The technology behind Lytro is probably the direction photography is taking. As virtual reality matures as a market, consumers will want to create in that medium. Because Lytro has the depth information for a scene, it can be used to create a 3d world.