Wow, that's some pretty efficient design there.
Reports are that the PS4 is more quiet than any version of the PS3 so it looks like that centrifugal fan is working properly
If this is true, then that means the PS4 will be quieter than quiet. I currently have a super-slim (I know that this version has a 45nm Cell BE chip from the original 90nm and the GPU is 40nm as opposed to the original 90nm) and it never makes any noise at all. The only times I've ever heard it was when it was initially reading a disc that was just inserted into it...
This is in stark contrast to the old 2008 partial-BC PS3 80GB model I had in early 2008, which sounded like a jet engine in its final days before it got the YLOD.
Except in this case bigger is better if it helps deal with heat.
PS4 has a lot of heat packed into a small space.
Xbox One has a lot less heat and larger space. I assume after last time, MS revised their industrial design to focus on the thing not dying, rather than making it as compact as possible.
Not necessarily. The PS4 may be compact, but no devs or people who have gotten the system early have been complaining about overheating issues. And as mentioned above, if this thing is really as quiet as they say it is, it's an incredibly efficient design. People would have to go out of their way to make one of these overheat.