Another open source Avonics system is from the Portland State Aerospace Society. http://psas.pdx.edu/AvionicsTeamHome/

Probably not as relevant as the Paparazzi team since they tend to fly straight up and straight down :) But if you are looking for alternative architectures (distributed processing) this might be of interest.

We (DANEnet) did several robotics groups in mandatory summer school a couple of years ago. We started kids off with Robosapiens. That is a controller based pre built robot. This was good for 1-2 sessions. Then we moved them onto the great Robodance program (free software to do visual programming on a pc using a USB wireless remote to control the Robosapiens). Another couple of sessions. Finally we went to Lego Robotics based program.

We lost some kids at each step. The step to Lego Robotics was particularly hard for these kids. One of the best groups was a mix of bilingual and solely Spanish speaking kids. Shades of the undocumented high school students that won a national college robotics competition http://www.wired.com/wired/archive/13.04/robot.html