It's actually rather exciting to see the dynamics of corporate-sponsored community work being actively discussed and studied. I've just learned (thanks to Matt Asay) of research, in prepublication state, on The Role of Participation Architecture in Growing Sponsored Open Source Communities. Unfortunately, this study only goes so far as to collect the reasons given by various companies and communities for why they chose to organize they way they did, principally in matters of "transparency" (read access to the code),  "accessibility" (write access to the code) and "governance" (the right to make decisions). As the study itself concludes, a useful next step would be to investigate whether these choices actually had the desired effect.

There are hints here that they do not. For example, it's common belief that the right to contribute code (what this study calls "accessibility") helps to grow the community. But the study points out that MySQL involves very little accessibility (more because a production-grade relational database server is HARD than any explicit policy), yet the MySQL community is extremely active (judged from mail list activity), both in user and developer areas. Explore at MarkMail (http://mysql.markmail.org/)