I've purchased an Aeon Labs USB stick to stick in the side of my old unused netbook, and am dabbling with python-openzwave. My first task was just to get the sensors (Aeon labs MultiSensor) recognised, and then start building some logic to monitor the temperature and turn on a fan if it rises above a threshold.
I've put some code up on github called flask-openzwave which I hope to grow as I learn more about Open ZWave.
Maybe foolishly, I decided this would be more fun than just buying a box (essentially another linux computer) pre-build with pre-made software. The only thing I'll miss is a nice Android app, but this can be mitigated by some keyfobs and a REST-like web interface. My wife will love it (maybe)...