Pneumatic Diversity Vent
The Aperture Science Pneumatic Diversity Vent is a game mechanic that was to originally intended to appear in Portal 2. The Vent was cut from the final release however, and instead only makes a few cameos. Valve has not released any statement on whether or not the Vents will make an appearance in any DLC. The Pneumatic Diversity Vent was first introduced as a testing element during the Portal ARG, in one of the ASCII art images given by the BBS.
Function
The Pneumatic Diversity Vent possesses a powerful vacuum, and will therefore suck up any object(s) placed below it. The vacuum also travels through Portals, and can therefore be used to to dispatch Turrets and other obstacles in multiple locations. The vacuum is also powerful enough to remove Panels from walls in some scenarios.
Aside from its ability to remove obstacles, it is presumed that the player would also have interacted with the Vents in order to move about rapidly, or to transport Weighted Storage Cubes or other such objects to other locations.
Demostration
Portal 2
While not appearing as a testing element in Portal 2, it can be seen several times.
See Also