GroundControl and MAVLink have been improved substantially behind the scenes over the last months. The most obvious new feature on the user level are custom user widgets. You can configure yourself parameter sliders and buttons and even export this widget into a *.qgw file, which other users can import. The video shows how to create a custom attitude control widget for ArduPilotMega. Most of the other improvements are speed and stability improvements which are not directly visible, but improve the user experience a lot. Since we wanted to make sure to get some testing done this is the first preview of the new version. Before end-users can test it, it will also require porting all autopilots, e.g. APM, to MAVLink v1.0.0, which is already scheduled and will happen in a few weeks. Porting is straightforward, as the C-API is mostly unchanged, only a few message signatures were updated.
Thanks to Andrew Tridgell and Paul Grobler for their contributions on the protocol. And Andrew Tridgell completely rebased the protocol generator on Python, allowing to now generate C and Python code from a single generator.
A porting guide for autopilots will be available soon.