It could be used as one. The 3d for nvidia's solution is to have a 120Hz screen essentially swapping eyes every frame, in essence giving each eye a 60Hz image. The image changes to what each eye would see each frame, and then the glasses take over. The active shutter glasses are synced with the transmitter to block whichever eye shouldn't see the frame being displayed at any given moment, e.g. if the left eye's frame is being displayed, the right eye is blocked by a shutter, thanks to persistence of vision, the shutter is unnoticeable to most people, especially at 120Hz which reduces the amount of headaches caused. This however does effectively halve the displayed fps when you look at the image, although the actual fps will remain largely the same, it has to be split up for two different images.
iz3d have a different technology which puts a polarising layer in front of a standard LCD. The drivers work out which bits of the image should be seen by which eye, and let the light out at angles, which are then negated by polarising glasses. It's a lot harder to explain this method, but it is less used now that nvidia have really started backing their option, however it doesn't cause headaches, is cheaper as the glasses don't have to have anything except mass produced lenses, and is also the 3d technology currently being implemented in pubs for sky sports, as it means if people steal the glasses or break them the pub isn't down £100 per pair.
gotta wait for the new nvidia cards. When i get 2 new 480gtxs ill start buying the components to run the pc
