What Do You Think of Steam OS and where do I get It?

try gabin's private email address

From Gabe.

http://store.steampowered.com/livingroom/SteamOS/

In short: "Downloadable soon. Free forever! SteamOS will be available soon as a free download for users and as a freely licensable operating system for manufacturers. Stay tuned in the coming days for more information."

So, be patient.