I recently wrote about kwikwai – device which is used to send control command over LAN, USB or RS232 to the AV equipment connected to it via HDMI. Actually it should replace old school IR transmitters to integrate AV equipment into whole house control system. RainShadow offers similar device but it works opposite way, i.e. it sens commands from AV equipment to the HTPC using HDMI-CEC technology. Currently the HDMI-CEC to USB and RS-232 bridge is supported by both Windows and Linux without custom device drivers.
If you’re interested to buy the HDMI-CEC to USB and RS-232 bridge you can do it now by reasonable price – $134 including international shipping.