3D pictures work by recreating what we see - because our eyes are set slightly apart, they each see a slightly different view of the world. Our brain combines those two images to create a sense of depth: the third dimension. 3D cameras capture 3D snaps by taking two pictures from slightly different angles and combining them. Most 3D cameras use two lenses so two images are captured with the right and left lens at the same time. Advanced image processing then merges the two images together to create a 3D image.
Most 3D cameras such as the Sony Alpha SLT- A55 and the Panasonic Lumix DMC-TZ20 take pictures and save them in the standard MPO format, which can be played back on 3D TVs or photo frames and require special glasses for the 3D effect. The Olympus TG-810 gives you the chance to take underwater 3D shots.
The Fujifilm Finepix is one camera where you can view your 3D pictures on the camera's screen without wearing 3D glasses. You can also capture video clips and then play them back in 3D on the spot.