Mosquitto MQTT broker which stopped it communicating with the Arduino. Since these technologies are new to me I assumed I was doing something wrong. However, Andy Stanford-Clark helped me figure out that if I switched to using the Really Small Message Broker (RSMB) I could get it working.
All that is left for me to do now is to make a little movie of my project demonstration. I intend using Kino for this. It is unlikely to be an Oscar contender, but it will also be the first time I used Kino for anything more than chopping up videos into pieces and/or converting between video formats.
I will also submit a bug report to Mosquitto so that it can be fixed.
I can't really blog about the project in detail outside of IBM. It is not a very complex project, but I am proud of it because it is my first real Arduino project and also the first time I used MQTT.