I've just about wrapped up QGroundControl Integration for the ArduPilotMega. The code currently implements the majority of the common protocol for QGroundControl. You can successfully read raw sensor gps/imu/gyro data, read radio packets, check the system status, check the system heartbeat, get/set pid gains and other control parameters (note they have yet to replace the current values for the controllers). Tomorrow I hope to have waypoint send/receive complete and to do a ground test with an RC car and a flight test if that is successful. Thanks PixHawk team for making a great ground station!