They’re both big, and they both run silent. At least that’s what I gathered from a Joystiq posting comparing how the PS3 runs compared to the noise-creating 360, which actually started to frighten my wife and I when I first fired it up. “Wait, what the hell is it doing … is that how it SOUNDS?” Yep.
The small posting explained how most of the heat generated in the PS3 leaves the machine via the large side vents, so it probably isn’t going to overheat, as poorly aired-out 360s have a tendency to do. Good to know. But it’s still the size of a small tombstone, so I have no idea where it would go in my home. Plus, I don’t want it to start waking up my toys or hurling eggs at the wall.