What do you mean by officially?

The C3 says on the heat spreader something to the effect of "Heatsink and Fan required".

The Eden chips are soldered onto the motherboard and come with a heatsink attached. The board is made by VIA, and the heatsink bears their logo. Below is a picture of my board. You can see more pics of the machine here. I use it as an MP3 server. I actually have it sitting in my stereo cabinet, so it had to be silent.