Nope, and it wont ever be possible on the N900 (unless you connect some extra hardware) because the PS3 has an extremely powerful CPU and graphics card, which is still more powerful then most of todays consumer hardware. (8core cpu and another heavy gpu).

So keep your expectations low, because you should be lucky with a ps1 emulator. I think even a PSP emulator would be extremely hard, because you emulate you need the power to play the game + the power to run the emulator.