I've been having great success playing with the Yun for controlling central heating kit with remote access.
The holy grail would be to plug in a Zwave USB Dongle and use it to work with the numerous zwave sensors and devices
http://www.vesternet.com/z-wave-aeon-labs-series-2-usb-controller
I have trawled the web looking for assistance, but as yet I can't find anything that guides one through how to install such a device on the yun. There is some stuff relating to the Raspberry Pi, as well as bits relating to Linux home automation...
http://domotiga.nl/projects/domotiga/wiki/Z-Wave_OpenZWave
All a bit much to get my head around at the moment, and any pointers or Yun specific tutorials would be much appreciated.