HI,
Currently I work on a new Amblight system. This system will use Enttec OpenDMX as hardware. So now it is possible to get 512 channels. 512 / 3 (red / green / blue) will make 170 possibles lights for ambilight.
The system will send a DMX signal, so all DMX lights will work on this signal.
More information about Enttec OpenDMX:
http://www.enttec.com/index.php?main_menu=Products&pn=70303&show=de_script_ion. Here can you found a schematic.
Also you can made your own DMX light, Google on DMX DIY. For example:
http://www.hoelscher-hi.de/hendrik/english/led.htmYou can found the program on my website:
http://gvrstudio.nl/send-the-light/ (Sorry it is Dutch, but the program is English)