Leaked PS4 user interface video
The part where the user interface was shown was actually an accident, the tester was trying out the Blacklight: Retribution demo on a test kit. It looked as if the game crashed, so we were able to see the tester go through the PS4 interface.
During the crash, the he says, "The kit was actually one of the first test kits to come out, so we will definitely crash. It's still optimizing. It's nowhere near alpha, let alone beta.."