The Minoru 3D webcam is supposedly the first consumer grade 3D webcam and while it has some rough edges it does look like an interesting sensor for robotics.
The concept behind the camera seems mostly like a gimmick based on the current popularity of 3D movies. The camera itself retails for about $90, which seems a little expensive when compared to what you can make yourself, but it might be worth it depending on what tools you have available. In terms of practical performance, on Linux I can get 30 frames per second from each camera at 320x240 resolution, and a little under 15fps at 640x480. The quality of the cameras is about what you would expect for two $45 cameras. Also worth noting, is that on my slower netbook, high frame rates tend to crash the system. I have not yet figured out why.
Bob Mottram has been working on developing software for supporting the camera on Linux and with ROS and he has provided extensive documentation here.
Here are some videos of his results which are fairly similar the the results I have obtained.
If you budget is a little more flexible, and your robot supports firewire you may be interested in the Videre Stereo Cameras as a higher performance alternative.
Do not buy this camera if you are expecting an out of the box 3D range finder. This camera is mostly interesting for people who want to write computer vision algorithms but don't want to deal with the mechanical issues of mounting the cameras together. The camera also provides acceptable results if your interest is producing anaglyphs. I am still waiting for the RGB-D cameras like the ones that should be shipping with Project Natal. Seriously, if you have not seen the RGB-D videos from Dr. Dieter Fox's lab, go here now. Hizook!!
If you are still interested you can buy the Minoru webcam here.