According to a report from VGLeaks, Sony's upcoming PlayStation 4 console will use a heavily modified version of the Linux operating system FreeBSD 9. According to the site, the PS4 will use a custom version of Free BSD 9 created by Sony called Orbis OS.
The PS4 uses an AMD eight-core APU with Radeon graphics, but there aren't any publicly available Catalyst drivers for any BSD operating system right now. The open-source driver ported from Linux with Radeon KMS and Gallium3D is still in a primitive state, according to the site. The speculation is that Sony has worked very closely with AMD to develop their own graphics driver for the PlayStation 4 with FreeBSD or ported the Catalyst code-base to BSD.
While this is interesting news, it is likely that Linux fans who were burned by the introduction of the OtherOS feature in the PS3 that was later removed by Sony over security issues has not been forgotten by people who wanted to run Linux on that platform. It is also highly unlikely that Sony will offer such a feature with the PS4...