K8, probably what you've seen is a "tilt/shift" or "perspective control" lens. They are lenses for SLR cameras the simulate the movements available on a large format view camera where you can tilt and shift either the lens board or the film plane. Since you can't actually swivel the front of the physical camera the lens itself allows movements to accommodate.
Basically the depth of field for a normal lens extends from one single fixed distance from the lens to another, all horizontally locked to the angle the lens is pointing, or "straight ahead" of the camera. If you can tilt or shift the lens, it also tilts or shifts that plane of focus vertically or horizontally which can then be combined with aperture to make it large or small, just not in the same place it would normally be.
And yes, sometimes shifting the field of focus gives that miniature or model-like feeling to your pictures.
I did this post processing I believe with gausian blur in photoshop. I hightlighted the bed with the magic wand and then reversed the highlight so everything else was highlighted with the magic wand and then blurred the background slowly. I was attemtping to copy a look that I've seen done with a particular lens, a lot of people I've heard call it a lens baby? idk what lens it is though, so I tried to make it look like images i've seen taken with that lens. It might not even be a real lens.
But what it creates are images that appear to be smaller than normal, if that makes sense. It's like it shrinks down the focal point and creates a really deep dof in the background. I dig the look, so I tried. I think it's a failure though. The image is alright, the bed looks smaller so I somewhat achieved the look. I think most people who know the ins and outs of photoshop can tell right away, like Gnortorious pointed out. at first glance it's ok, but then you really look and you're like ohhhh...well thats just a blur. plsu if you look closely around the head board you can see where I didn't completely have the bed highlighted and had parts of the wall highlighted so it looks funky.
it was my first attempt wwwweeeeeeeee