Maturity models are certainly proliferating. There are scores of them, evaluating everything from software to enterprise architecture. Many are freely available, some are proprietary. At least three exist for evaluating open source software.
When the Open ePolicy Group was developing the "Roadmap for Open ICT Ecosystems," there was considerable debate over whether we should offer a new maturity model. We saw a gap; we found no maturity model that gauged the openness of an entire ICT ecosystem. Maturity models, like people, tend to work in silos.
Not everyone in the Group, however, wanted to cast yet another maturity model out into the world. In the end, we decided to offer our Openness Maturity Model, not to guide any specific decision (e.g., choosing software) but rather to help policymakers and managers aggregate baseline data and chart a path toward more open ICT ecosystems.
Early feedback seems to validate our decision. People continue to say (most recently during my Roadmap presentation in Brazil last week) that the Openness Maturity Model is the single most useful thing in the Roadmap. People like tools, I guess. Though this one could still benefit from some more work under the hood, and it remains our hope that others will help develop it further using our wiki: http://wiki.openization.org