Cairo for graphics, Squeak (a dialect of Smalltalk) for programming, ECMAScript, written in C++, and runs on x86 and Qemu. It's quite a huge accomplishment but not exactly surprising that it exists when you realize that Nintendo games are operating systems in themselves.The source is freely available so those with some knowhow and time to kill can mess around with it.
What the...
If either Nintendo or Sony made an OS, I thought it would be Sony :O
I never once expected Nintendo to do it, must check this out.