PlayStation 4 runs modified FreeBSD 9.0: 'Orbis OS'
 

Pretty cool stuff: the PlayStation 4 apparently runs on a version of FreeBSD 9.0 modified by Sony and renamed to 'Orbis OS'. Second generation developer kits use GNU GRUB to boot, and allow you to boot into a graphical or a console mode. Not much else is known at this point, but it's a fun bit of information, and perhaps a boon to homebrew developer and hackers.

http://osnews.com/story/27145/PlaySt..._9_0_Orbis_OS_