Google gets a lot of praise for bringing open source to the masses with Android, and a lot of flack for some of its more closed-off activities. On a technical level the company complies with the fundamental principles of open source software, but not always in the way that FOSS proponents would like. A perfect example is Android 3.0 Honeycomb, which never saw an open source release until version 4 was already available. These tendencies and more technical details led VisionMobile to rank it the "most closed" open source OS among a field of the most popular examples.
In a series of metrics, Google's Android scored just 23% "open", comparing poorly to the likes of Linux, Symbian and Meego. The running wasn't limited to operating systems - Mozilla's various open source tools, the Webkit browser framework and the QT user interface toolkit were also included. VisionMobile based their ratings on a variety of factors, such as the licenses used, the strictness by which the community is enforced, and the level of access that developers are given to the development process. For a more technical breakdown, head over to the source link above.
There's no denying that Google keeps a pretty tight lid on Android, at least until the source code is released. In the case of the G1, original DROID, Nexus One, XOOM, Nexus S and Galaxy Nexus, only Google's software engineers and its hardware partners had access to the software until well after a flagship device was released. On the other hand, Google's aggressive promotion of Android has allowed it to become one of the most widely-used pieces of open source software in history, giving manufacturers, developers and tinkerers a complete and free ecosystem - eventually. VisionMobile concludes that Google's promotional machine is a double-edged sword for Android, broadening its horizons while keeping its core interest well within the commercial spectrum.