ArduSat is an open-source arduino-based CubeSat. It plans to have an extensive sensor-suite onboard that will allow users to upload their own code and run their own experiments.
Watch KickStarter ArduSat
[youtube http://www.youtube.com/watch?v=cunWXI_UJe8]
Open Satellite Network https://sites.google.com/a/hackersinspace.net/www/