We use a Kinect camera connected directly to our coprocessor, which is then processed by OpenCV, and then sent to the RoboRIO / Driver Station for alignment and viewing. Running on a single thread, the coprocessor is able to update at the Kinect's maximum framerate of 30FPS.
Here's a video of it in action (with a handheld piece of cardboard with retroreflective tape. Coprocessor and RoboRIO are running in this example)