it is already possible to use Dual Shock 3 with maemo (not specifically related to psx emulator). I'm using it already with this emulator sometimes and it works great. the only issues with it is that this emulator does not support the analog sticks (for example MAME emulator supports it very well) and vibration (would be very nice to have them also of course). There are several threads about pairing a DS3 with N900 - this is one of them: http://talk.maemo.org/showthread.php?t=32887