tilt shift madness

i stumbled upon a type of photography called tilt shift lens photography. what is it exactly? i came across this brief definition on photonotes.org: "Tilt-shift lenses (can be used for shifting or perspective control)...The lenses can also tilt, which lets you move the optical axis away from the perpendicular of the film plane. Normally the optical axis of a lens is precisely perpendicular (90°) from the film surface, but tilt lenses let you alter this angle, which is useful for altering what parts of an image are within the depth of field and are thus in focus."

take from that what you may. all I know is that some of the images are amazing -- notice how these pictures look like miniature models:






a cool photoblog with examples. click HERE.

and a site with good info about tilt/shift lenses. click HERE.