Researchers at a German university have built an apparatus that, while clunky in its proof-of-concept stage, could assist the blind as they cross streets, walk down hallways and open doors. It uses the Kinect as a sensor.
In lay terms, how it works is that it scans the environment for special placards with symbols on them. Once recognized, the system's audio relays to its wearer the distance of the next objective (a doorway, for example) and its position.
So for example, if you walk towards a door the output will be "Door ahead in 3″, "2″, "1″, "pull the door" where each part of the information depends on the distance to the marker on the door.
The device includes a vibration motor in the belt, whose pulse gets stronger as the wearer approaches an objective, presumably as a redundant alert. You can see how it all works in that video above. A blindfolded user was able to navigate a short course with it.
Kinect Bringing Sight to the Blind, Sorta [Slashgear, thanks adinnieken]