Ofcourse the ps3 makes sound, but it should be so low that it gets drowned out by other sounds easily, like from a tv. An xbox 360 should be a lot louder since the drive spins at 12x ( its like a pc drive).
Seriously, perhaps your friends ps3 is gathering too much dust or something, getting too hot and thus making the fan work harder.


TEST
I just tested it, and my Wii actually makes more sound then my ps3, its so low that its practically inaudible with any other source of sound in the vicinity.