Since the demise of MeeGo a group of people have been involved with taking the best elements of that project along with a dose of new ideas to create the Mer Project. This project is aimed not at end users but at people, and companies who are or want to produce products. Mer provides a core set of fully maintained packages which can be used to build products in the mobile and embedded markets providing Qt/HTML5/JS API's. Because the core is maintained by the Mer project resources are not required by each manufacturer so has obvious cost savings. Mer is just the core and needs two elements to be added to make a full software stack for a product. A device adaptation is required to sit below the Mer core and provides a well defined interface to it. The adaptation is made up of a Linux kernel, graphics and network drivers, sound and device configurations, things which will be different for each product. The other element required is a user interface or user experience (UX) layer and this is where device manufacturers can provide differentiation for their product, the look and feel. Mer core will provide a rich set of API's to build the UX layer with modern API's such as Qt/QML and HTML5 ensuring the best possible experience for the end user.
The Mer core set of packages is around 300 and these are stored in git repositories and a change mechanism has been implemented using a set of opensource tools which allow for both human and automatic review processes, each change is sent to a build system to ensure changes don't break the whole build. Plans are in place to offer automatic testing of all changes to the core after code review and build test. These processes are in large part automatic and provide the level of tracking an OEM will need especially in the area of license management and compliance.
The project is open source and has a draft governance document based on the Yocto project and is in review at the moment. You can read it here and comment to the mailing list.
The project has a growing wiki page and this is also where you can find details of the projects surrounding Mer the community workspace, where you can find details of the progress of the device adaptations and user experiences already built on Mer Core. You will see from that page that there are a number of devices running a diverse set of user experiences and this is just after a few weeks since the project launch.
As an example I've been involved in device adaptations to the Advent Vega Tablet and compulab Trimslice, both nVidia Tegra devices and also in integration of the Plasma Active UX on those devices and to the Nokia N950.
If you want to know more about Mer and the community projects surrounding drop into #Mer on freenode IRC.