[bonzini]

Red Hat hires a lot of fresh college graduates rather than aiming at existing "open source stars". Many then grow to become the maintainers of the projects they work on, and choose to stay in the company that let them grow. This is different from many other companies which hire current maintainers for public work and have the younger ones work more behind closed doors.

(I work at RH, but actually I heard the above observation first here on HN from someone that is at Google).