Actually, it's not just one camera. Depending on the application, RealSense is either two cameras (if the application is just for creating 3D images) or three cameras (if the application is for taking high-res 2D images to which 3D depth information is applied), as is the case with Dell's Venue 8 7000.
Now, I can't tell you it's convenient, having three cameras on the back of your tablet, the way the Venue 8 does. It makes it hard to hold the tablet without your fingers covering at least one of the cameras. But it does make for some interesting applications, most of which are yet to be fully realised but which do seem very promising indeed.
RealSense works by having two cameras spaced a certain distance apart, that each record images of the same objects but from a slightly different angle. Algorithms inside the technology analyse the difference between the two images and use that difference to create a 3D model of the objects, complete with depth perception, in much the same way the human brain does.
Then, in the case of the three-camera Dell, that 3D information is added as metadata to images taken with the main camera, allowing for all sorts of neat tricks.
One trick, the trick that works best at the moment, is measuring things. Because the RealSense has calculated how far objects are away from the camera, the Dell's camera app is able to tell you how big things are. You just drag a virtual measuring tape over things in photos, and it tells you their size.
We've tested it under a variety of conditions, and it's surprisingly accurate most of the time. All of those measurements above, when we double checked them in the real world with a tape measure, were accurate.