Willow Garage open sourced the software they use to run their PR2 robot
I think Willow Garage almost had to because they were using lots of open source tools in the first place. ROS is based on playerstage, which is GPL, and a lot of the heavy computer vision stuff is OpenCv, which itself was originally open-sourced by Intel. And the deal with everyone using ROS had a lot to do with development shifting from playerstage to ROS 'cause they were similar but ROS was saner, so they became the standard in large part 'cause they improved on the existing open source standard rather then trying to create some kind of large scale shift in the community. Plus, Willow Garage is as much experimental lab as company, so I don't know if it works as a good case study 'cause it sort of has a weird mix of end goals.
Willow Garage also gained a lot of cred by taking over OpenCV from intel and actively maintaining it, which isn't something a fledgling company can do but is worth considering. They adopted the library 'cause it was critical to their business and considered something of a standard in the vision community, which meant a lot of people were already using it, so it was popular enough that maintaining it was seen as a good thing.