The game — which was described as jaw-dropping by ex-employees recently — was cancelled in 2008 due to spiralling development costs and a refocusing of first-party projects within Sony Worldwide Studios.
The footage itself appears to be based on an old build of the game, presumably representing a snap-shot of its development status before being cancelled. There's certainly no indication of the game making a come-back.
If you hate money, you could probably place a bet on the game being reannounced at Sony's GamesCom press conference tomorrow, but we don't recommend it.
Either way, the footage itself is intriguing. Watch it after the break.