Mozilla is building an OS for mobile devices called the Boot 2 Gecko(B2G) project. Firefox B2G is similar--an open source project which aiming to clean up mobile fragmentation.
Understanding that building a platform from the ground up is quite a challenge, Mozilla is using some of the open-source code from Google's Android for helping interact with the mobile hardware. The OS will have an entirely different UI and application stack, which will be pulled from Firefox's cross-platform layout engine Gecko.
One key differentiator from Android, Mozilla stated that they will not be relying on the Java language that is popular with the Android system.
Mozilla has already put a prototype on display at the Mozilla Labs' Concept Series. The prototype was given the name Seabird.
