LinuxMCE can control thermostats that are X10 compatible.
Manufacturer: [RCS] This thermostat provides bi-directional X10 communication. Unfortunately, it uses up all 16 addresses of a house code. It consists of 2 parts, a wall display unit and a control unit. The wall display unit contains the temperature sensor, a LCD screen for temperature and setting outputs, buttons for raising or lowering the temperature, and should be installed where the old thermostat is attached.
The control unit is a bit ugly so it should be hidden in the boiler room or a closet. This unit contains the X10 control interface and has an X10 wall plug that needs to be plugged into an outlet. It also has another wall plug for power. Yes, that's 2 wall plugs - one for X10 communication, and one for power.