OpenCV is a open source computer vision library, originally an Intel initiative now supported by Willow Garage. Intel started off this initiative, partly to compete in the non -PC market. Intel processors were not a preferred choice for DSP or image processing applications. So by starting of this open source computer vision library initiative Intel will be able to lure customers to use its processors, since most of the OpenCV was developed and tested on Intel processors. I think there were also few acquisition's on Intel, that OpenCV gave better preforamnce on Intel processors when compared to others. Now OpenCV is supported by Willow Garage, a robotics research lab and technology incubator. The huge advantage that I think Willow Garage has is, since OpenCV is vital for robotics application, it can benefit from the community developing the library, while Willow Garage can sell its robotics hardware using this library to develop software for their robots.
A similar open source initiative is OpenGL, a graphics library. OpenGL was started off by Silicon Graphics. This was made open source because there were lots o hardwares/GPU's released by various vendors in the market. Silicon Graphics had to spend lot its resources to develop applications for each of these hardwares. By making OpenGL open source it benefits from the community that can develop the each hardware specific API's, so that OpenGL will act as a common graphics library. So that Silicon Graphics can spend all its resources developing its complete application using OpenGL.
Ubuntu ,Red Hat and Novell are probably well know examples of this open source business. Both Red Hat and Novell develop a free versions of Linux as well a paid service that comes along with support. However Ubuntu driven by Canonical Ltd, sells Ubuntu for free, but sells training and support for Ubuntu.