Sony's Playstation 4 will be running a modified version of FreeBSD 9 OS.

It has been revealed that the PS4's operating system is Orbis OS, which is a Sony modified FreeBSD 9.0. Sony has chosen to use FreeBSD over Linux, in part due to the more liberal licensing. It's a bit surprising to see FreeBSD being used when at the heart of the PS4 is an AMD 8-core APU with Radeon graphics. Because there isn't a Catalyst driver available for any BSD OS, Sony in cooperation with AMD must have developed their own graphics drivers for the Playstation 4.

-Erik