The GPL may be a community-building signalling device, but it is also a confession of fear and weakness. To believe that it matters, you have to believe that you live in a Type A universe where closed-source development is such an attractive proposition that you have to punish people for trying to move to it.
Rather than sell software licenses for static, hard-to-customize software products, we're informing libraries about the benefits of open source, enabling them to make choices about how best to provide their communities and staff with better technology services.
S. Koch, S. Strecker, and U. Frank. Open Source Systems, Proceedings of The Second International Conference on Open Source Systems, IFIP Working Group 2.13 Foundation on Open Source Software, June 8--10, 2006, Como, Italy, volume 203 of IFIP International Federation for Information Processing Series, Springer, Berlin, (2006)