For quite some time a while back I was working on a port of FreeRTOS for Arduino (ArduiOS). I haven’t had time to work on this project for a while now, but all the repositories where I kept my work are available here:

https://bitbucket.org/luckyspicer/arduinos

https://bitbucket.org/luckyspicer/arduino-eclipse-projects

https://bitbucket.org/luckyspicer/arduino-custom-libraries

https://bitbucket.org/luckyspicer/arduino-sketchbook